UrbanPro

Your Worksheet is Ready

CBSE - Class 10 Mathematics Applications of Trigonometry Worksheet

1.

A circus artist is climbing a $20$ m long rope, which is tightly stretched and tied from the top of a vertical pole to the ground. Find the height of the pole, if the angle made by the rope with the ground level is $30°$ (see Fig. 9.11).

 

2.
A $1.5$ m tall boy is standing at some distance from a $30$ m tall building. The angle of elevation from his eyes to the top of the building increases from $30°$ to $60°$ as he walks towards the building. Find the distance he walked towards the building.
3.
A kite is flying at a height of $60$ m above the ground. The string attached to the kite is temporarily tied to a point on the ground. The inclination of the string with the ground is $60°$. Find the length of the string, assuming that there is no slack in the string.
4.
A straight highway leads to the foot of a tower. A man standing at the top of the tower observes a car at an angle of depression of $30°$, which is approaching the foot of the tower with a uniform speed. Six seconds later, the angle of depression of the car is found to be $60°$. Find the time taken by the car to reach the foot of the tower from this point.
5.
Two poles of equal heights are standing opposite each other on either side of the road, which is $80$ m wide. From a point between them on the road, the angles of elevation of the top of the poles are $60°$ and $30°$, respectively. Find the height of the poles and the distances of the point from the poles.
6.
The angle of elevation of the top of a building from the foot of the tower is $30°$ and the angle of elevation of the top of the tower from the foot of the building is $60°$. If the tower is $50$ m high, find the height of the building.
7.
A contractor plans to install two slides for the children to play in a park. For the children below the age of $5$ years, she prefers to have a slide whose top is at a height of $1.5$ m, and is inclined at an angle of $30°$ to the ground, whereas for elder children, she wants to have a steep slide at a height of $3$m, and inclined at an angle of $60°$ to the ground. What should be the length of the slide in each case?
8.
A statue, $1.6$ m tall, stands on the top of a pedestal. From a point on the ground, the angle of elevation of the top of the statue is $60°$ and from the same point the angle of elevation of the top of the pedestal is $45°$. Find the height of the pedestal.
9.
The angle of elevation of the top of a tower from a point on the ground, which is $30$ m away from the foot of the tower, is $30°$. Find the height of the tower.
10.
From a point on the ground, the angles of elevation of the bottom and the top of a transmission tower fixed at the top of a $20$ m high building are $45°$ and $60°$ respectively. Find the height of the tower.
11.

A $1.2$ m tall girl spots a balloon moving with the wind in a horizontal line at a height of $88.2$ m from the ground. The angle of elevation of the balloon from the eyes of the girl at any instant is $60°$. After some time, the angle of elevation reduces to $30°$ (see Fig. 9.13). Find the distance travelled by the balloon during the interval.

12.
As observed from the top of a $75$ m high lighthouse from the sea-level, the angles of depression of two ships are $30°$ and $45°$. If one ship is exactly behind the other on the same side of the lighthouse, find the distance between the two ships.
13.
From the top of a $7$ m high building, the angle of elevation of the top of a cable tower is $60°$ and the angle of depression of its foot is $45°$. Determine the height of the tower.
14.

A TV tower stands vertically on a bank of a canal. From a point on the other bank directly opposite the tower, the angle of elevation of the top of the tower is $60°$. From another point $20$ m away from this point on the line joing this point to the foot of the tower, the angle of elevation of the top of the tower is $30°$ (see Fig. 9.12). Find the height of the tower and the width of the canal.

15.
A tree breaks due to storm and the broken part bends so that the top of the tree touches the ground making an angle $30°$ with it. The distance between the foot of the tree to the point where the top touches the ground is $8$ m. Find the height of the tree.

Worksheet Answers

Solution:

Given:

  • Length of the rope ($AC$) = $20$ m.
  • Angle made by the rope with the ground level ($\angle C$) = $30^\circ$.
  • The pole is vertical, meaning the angle between the pole and the ground is $90^\circ$ ($\angle B = 90^\circ$).

To Find:

  • The height of the pole ($AB$).

Visual Representation:

20 m h 30° C B A

Step 1: Defining the Variables and Trigonometric Relationship

Let $AB$ be the height of the vertical pole. Let $AC$ be the length of the rope. In the right-angled triangle $\triangle ABC$, where $\angle B = 90^\circ$:

  • The side opposite to the angle $\angle C$ is $AB$ (the height of the pole).
  • The side opposite to the right angle $\angle B$ is $AC$ (the hypotenuse, which is the rope).

We use the trigonometric ratio that relates the opposite side and the hypotenuse, which is the sine function:

$\sin(\theta) = \frac{\text{Opposite}}{\text{Hypotenuse}}$

Step 2: Setting up the Equation

Substituting the known values into the sine formula:

$\sin(30^\circ) = \frac{AB}{AC}$

Given that $AC = 20$ m and $\sin(30^\circ) = \frac{1}{2}$ [Standard trigonometric value]:

$\frac{1}{2} = \frac{AB}{20}$

Step 3: Solving for $AB$

To isolate $AB$, multiply both sides of the equation by $20$:

$AB = 20 \times \frac{1}{2}$

$AB = 10$

Step 4: Conclusion

The height of the pole is $10$ meters.

Final Answer: The height of the pole is 10 m.

Solution:

Given:

  • Height of the building ($AB$) = $30$ m.
  • Height of the boy ($ED = FC$) = $1.5$ m.
  • Initial angle of elevation ($\angle AEF$) = $30^\circ$.
  • Final angle of elevation ($\angle ADF$) = $60^\circ$.

To find:

The distance the boy walked towards the building, which is the distance $EF$.

A B E D F 30° 60°

Step 1: Determine the height of the triangle above the boy's eye level.

Let the building be $AB$ and the boy's positions be $EF$ and $DC$. The height of the building $AB = 30$ m. Since the boy is $1.5$ m tall, the height of the triangle $AF$ (where $F$ is the point on $AB$ at the eye level of the boy) is:

$AF = AB - FB = 30 - 1.5 = 28.5$ m.

Step 2: Define the variables for the horizontal distances.

Let $DF = x$ and $EF = y$. We need to find $x$.

Step 3: Apply trigonometry in $\triangle ADF$.

In the right-angled triangle $\triangle ADF$, the angle of elevation is $60^\circ$.

Using the tangent ratio: $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$

$\tan(60^\circ) = \frac{AF}{DF}$

Since $\tan(60^\circ) = \sqrt{3}$:

$\sqrt{3} = \frac{28.5}{x}$

$x = \frac{28.5}{\sqrt{3}}$

Rationalizing the denominator: $x = \frac{28.5 \times \sqrt{3}}{3} = 9.5\sqrt{3}$ m.

Step 4: Apply trigonometry in $\triangle AEF$.

In the right-angled triangle $\triangle AEF$, the angle of elevation is $30^\circ$.

$\tan(30^\circ) = \frac{AF}{EF} = \frac{AF}{ED + DF}$

Since $\tan(30^\circ) = \frac{1}{\sqrt{3}}$:

$\frac{1}{\sqrt{3}} = \frac{28.5}{y + x}$

$y + x = 28.5\sqrt{3}$

Step 5: Calculate the distance walked ($y$).

$y = 28.5\sqrt{3} - x$

$y = 28.5\sqrt{3} - 9.5\sqrt{3}$

$y = 19\sqrt{3}$ m.

Final Answer: The distance the boy walked towards the building is $19\sqrt{3}$ m.

Solution:

Given:

1. The height of the kite above the ground ($AB$) = $60$ m.

2. The angle of inclination of the string with the ground ($\angle ACB$) = $60^\circ$.

3. The string is assumed to be taut (no slack), forming a straight line.

To Find:

The length of the string ($AC$).

A (Kite) B C (Point on ground) 60 m 60°

Step 1: Defining the Geometric Model

Let the position of the kite be point $A$, the point on the ground directly below the kite be $B$, and the point where the string is tied to the ground be $C$.

This forms a right-angled triangle $\triangle ABC$, where:

  • $\angle B = 90^\circ$ (The height is measured perpendicular to the ground).
  • $AB = 60$ m (The side opposite to $\angle C$).
  • $\angle C = 60^\circ$ (The angle of inclination).
  • $AC$ is the length of the string (the hypotenuse of the triangle).

Step 2: Selecting the Trigonometric Ratio

In a right-angled triangle, the relationship between the side opposite to an angle and the hypotenuse is given by the sine function:

$\sin(\theta) = \frac{\text{Opposite}}{\text{Hypotenuse}}$

Applying this to $\triangle ABC$:

$\sin(60^\circ) = \frac{AB}{AC}$

Step 3: Substituting Known Values

We know that $\sin(60^\circ) = \frac{\sqrt{3}}{2}$ [Standard trigonometric value].

Substituting the values into the equation:

$\frac{\sqrt{3}}{2} = \frac{60}{AC}$

Step 4: Solving for $AC$

To isolate $AC$, we perform cross-multiplication:

$\sqrt{3} \times AC = 60 \times 2$

$\sqrt{3} \times AC = 120$

$AC = \frac{120}{\sqrt{3}}$

Step 5: Rationalizing the Denominator

To simplify the expression, multiply the numerator and denominator by $\sqrt{3}$:

$AC = \frac{120}{\sqrt{3}} \times \frac{\sqrt{3}}{\sqrt{3}}$

$AC = \frac{120\sqrt{3}}{3}$

$AC = 40\sqrt{3}$

Step 6: Final Calculation

Using the approximation $\sqrt{3} \approx 1.732$:

$AC = 40 \times 1.732 = 69.28$ m

Final Answer: The length of the string is $40\sqrt{3}$ m or approximately $69.28$ m.

Solution:

Given:

1. A tower $AB$ of height $h$ stands vertically on a horizontal plane.

2. A car is moving towards the foot of the tower ($B$) along a straight highway.

3. At point $C$, the angle of depression from the top of the tower ($A$) is $30^\circ$.

4. After $6$ seconds, the car reaches point $D$, where the angle of depression is $60^\circ$.

To Find:

The time taken by the car to travel from point $D$ to the foot of the tower $B$.

A B C D 60° 30°

Step 1: Define Variables and Geometric Relationships

Let $AB = h$ be the height of the tower. Let the speed of the car be $v$ (units/sec).

Distance covered by the car from $C$ to $D$ in $6$ seconds is $CD = v \times 6 = 6v$.

Let the time taken to travel from $D$ to $B$ be $t$ seconds. Then, $DB = v \times t = vt$.

Step 2: Apply Trigonometric Ratios in Right-Angled Triangles

In $\triangle ABD$ (where $\angle ADB = 60^\circ$):

$\tan(60^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{AB}{DB}$

Since $\tan(60^\circ) = \sqrt{3}$, we have:

$\sqrt{3} = \frac{h}{vt} \implies h = vt\sqrt{3}$ --- (Equation 1)

In $\triangle ABC$ (where $\angle ACB = 30^\circ$):

$\tan(30^\circ) = \frac{AB}{CB} = \frac{AB}{CD + DB}$

Since $\tan(30^\circ) = \frac{1}{\sqrt{3}}$, we have:

$\frac{1}{\sqrt{3}} = \frac{h}{6v + vt}$

$h\sqrt{3} = 6v + vt$ --- (Equation 2)

Step 3: Solve the System of Equations

Substitute the value of $h$ from Equation 1 into Equation 2:

$(vt\sqrt{3})\sqrt{3} = 6v + vt$

$vt(3) = 6v + vt$

$3vt = 6v + vt$

Subtract $vt$ from both sides:

$2vt = 6v$

Divide both sides by $2v$ (assuming $v \neq 0$):

$t = \frac{6v}{2v}$

$t = 3$

Conclusion:

The time taken by the car to travel from point $D$ to the foot of the tower $B$ is $3$ seconds.

Final Answer: 3 seconds

Solution:

Given:

  • Two poles of equal height, let this height be $h$ meters.
  • The width of the road is $80$ m.
  • A point $P$ is located on the road between the two poles.
  • The angle of elevation from point $P$ to the top of the first pole is $60^\circ$.
  • The angle of elevation from point $P$ to the top of the second pole is $30^\circ$.

To Find:

  • The height of the poles ($h$).
  • The distance of point $P$ from each pole.
A B C D P 60° 30° 80 m

Step 1: Define variables and set up the geometry.

Let the two poles be $AC$ and $BD$ such that $AC = BD = h$.
Let the width of the road $CD = 80$ m.
Let $P$ be a point on $CD$ such that $CP = x$ meters. Then, $PD = (80 - x)$ meters.

Step 2: Apply trigonometric ratios in the right-angled triangles.

In $\triangle ACP$, using the tangent ratio $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$:

$\tan(60^\circ) = \frac{AC}{CP}$

$\sqrt{3} = \frac{h}{x}$

$h = x\sqrt{3}$ --- (Equation 1)

In $\triangle BDP$:

$\tan(30^\circ) = \frac{BD}{PD}$

$\frac{1}{\sqrt{3}} = \frac{h}{80 - x}$

$h = \frac{80 - x}{\sqrt{3}}$ --- (Equation 2)

Step 3: Solve for $x$.

Equating Equation 1 and Equation 2:

$x\sqrt{3} = \frac{80 - x}{\sqrt{3}}$

Multiply both sides by $\sqrt{3}$:

$3x = 80 - x$

$3x + x = 80$

$4x = 80$

$x = 20$ m

Step 4: Calculate the height $h$ and the remaining distance.

Substitute $x = 20$ into Equation 1:

$h = 20\sqrt{3}$ m

The distance of point $P$ from the first pole is $CP = x = 20$ m.

The distance of point $P$ from the second pole is $PD = 80 - x = 80 - 20 = 60$ m.

Final Answer: The height of the poles is $20\sqrt{3}$ m (approx. $34.64$ m), and the distances of the point from the poles are $20$ m and $60$ m respectively.

Solution:

Given:

  • Height of the tower ($CD$) = $50$ m.
  • Angle of elevation of the top of the building ($AB$) from the foot of the tower ($D$) = $30^\circ$.
  • Angle of elevation of the top of the tower ($CD$) from the foot of the building ($B$) = $60^\circ$.

To find:

The height of the building ($AB = h$).

A B C D 30° 60°

Step 1: Define variables and identify triangles.

Let the height of the building $AB = h$ meters.

Let the distance between the foot of the building ($B$) and the foot of the tower ($D$) be $BD = x$ meters.

We have two right-angled triangles: $\triangle ABD$ and $\triangle CDB$.

Step 2: Analyze $\triangle CDB$ to find the distance $x$.

In $\triangle CDB$, the angle of elevation is $\angle CBD = 60^\circ$.

Using the trigonometric ratio tangent: $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$

$\tan(60^\circ) = \frac{CD}{BD}$

Since $\tan(60^\circ) = \sqrt{3}$ [Trigonometric table value]:

$\sqrt{3} = \frac{50}{x}$

$x = \frac{50}{\sqrt{3}}$ --- (Equation 1)

Step 3: Analyze $\triangle ABD$ to find the height $h$.

In $\triangle ABD$, the angle of elevation is $\angle ADB = 30^\circ$.

Using the trigonometric ratio tangent:

$\tan(30^\circ) = \frac{AB}{BD}$

Since $\tan(30^\circ) = \frac{1}{\sqrt{3}}$ [Trigonometric table value]:

$\frac{1}{\sqrt{3}} = \frac{h}{x}$

$h = \frac{x}{\sqrt{3}}$ --- (Equation 2)

Step 4: Substitute Equation 1 into Equation 2.

$h = \frac{\frac{50}{\sqrt{3}}}{\sqrt{3}}$

$h = \frac{50}{\sqrt{3} \times \sqrt{3}}$

$h = \frac{50}{3}$

$h = 16.666...$ meters

Final Answer: The height of the building is $\frac{50}{3}$ m or approximately $16.67$ m.

Solution:

Given:

Case 1 (Children below 5 years):

  • Height of the slide ($AB$) = $1.5$ m
  • Angle of inclination ($\angle ACB$) = $30^\circ$

Case 2 (Elder children):

  • Height of the slide ($PQ$) = $3$ m
  • Angle of inclination ($\angle PRQ$) = $60^\circ$

To find:

The length of the slide for each case (i.e., the length of the hypotenuse $AC$ and $PR$).

1.5m AC 30° 3m PR 60°

Step 1: Calculating the length of the slide for children below 5 years.

In the right-angled triangle $\triangle ABC$, where $\angle B = 90^\circ$:

We use the trigonometric ratio that relates the opposite side to the hypotenuse, which is the sine function:

$\sin(\theta) = \frac{\text{Opposite}}{\text{Hypotenuse}}$

Substituting the given values:

$\sin(30^\circ) = \frac{AB}{AC}$

Since $\sin(30^\circ) = \frac{1}{2}$ [Standard trigonometric value]:

$\frac{1}{2} = \frac{1.5}{AC}$

By cross-multiplication:

$AC = 1.5 \times 2$

$AC = 3$ m

Step 2: Calculating the length of the slide for elder children.

In the right-angled triangle $\triangle PQR$, where $\angle Q = 90^\circ$:

Using the sine function again:

$\sin(60^\circ) = \frac{PQ}{PR}$

Since $\sin(60^\circ) = \frac{\sqrt{3}}{2}$ [Standard trigonometric value]:

$\frac{\sqrt{3}}{2} = \frac{3}{PR}$

By cross-multiplication:

$PR \times \sqrt{3} = 3 \times 2$

$PR \times \sqrt{3} = 6$

$PR = \frac{6}{\sqrt{3}}$

Rationalizing the denominator by multiplying the numerator and denominator by $\sqrt{3}$:

$PR = \frac{6 \times \sqrt{3}}{\sqrt{3} \times \sqrt{3}}$

$PR = \frac{6\sqrt{3}}{3}$

$PR = 2\sqrt{3}$ m

Using the approximation $\sqrt{3} \approx 1.732$:

$PR \approx 2 \times 1.732 = 3.464$ m

Final Answer: The length of the slide for children below 5 years is $3$ m, and the length of the slide for elder children is $2\sqrt{3}$ m (approximately $3.46$ m).

Solution:

Given:

  • Height of the statue ($AB$) = $1.6$ m.
  • The statue stands on a pedestal ($BC$).
  • Angle of elevation from a point $D$ on the ground to the top of the statue ($A$) is $\angle ADB = 60^\circ$.
  • Angle of elevation from the same point $D$ to the top of the pedestal ($B$) is $\angle CDB = 45^\circ$.

To Find:

The height of the pedestal ($BC = h$ meters).

A B C D Ground 1.6m h

Step 1: Define Variables and Assumptions

Let $BC = h$ be the height of the pedestal in meters.

Let $CD = x$ be the distance from the point $D$ to the base of the pedestal $C$ in meters.

The total height of the statue and pedestal is $AC = AB + BC = 1.6 + h$.

Step 2: Analyze the smaller triangle $\triangle BCD$

In the right-angled triangle $\triangle BCD$, the angle $\angle CDB = 45^\circ$.

Using the trigonometric ratio $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$:

$\tan(45^\circ) = \frac{BC}{CD}$

Since $\tan(45^\circ) = 1$:

$1 = \frac{h}{x} \implies x = h$ --- (Equation 1)

Step 3: Analyze the larger triangle $\triangle ACD$

In the right-angled triangle $\triangle ACD$, the angle $\angle ADB = 60^\circ$.

Using the trigonometric ratio $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$:

$\tan(60^\circ) = \frac{AC}{CD}$

Substitute $AC = 1.6 + h$ and $CD = x$:

$\sqrt{3} = \frac{1.6 + h}{x}$ --- (Equation 2)

Step 4: Solve for $h$

Substitute $x = h$ (from Equation 1) into Equation 2:

$\sqrt{3} = \frac{1.6 + h}{h}$

Multiply both sides by $h$:

$h\sqrt{3} = 1.6 + h$

Rearrange the terms to isolate $h$:

$h\sqrt{3} - h = 1.6$

$h(\sqrt{3} - 1) = 1.6$

$h = \frac{1.6}{\sqrt{3} - 1}$

Step 5: Rationalize the denominator

To simplify, multiply the numerator and denominator by the conjugate $(\sqrt{3} + 1)$:

$h = \frac{1.6(\sqrt{3} + 1)}{(\sqrt{3} - 1)(\sqrt{3} + 1)}$

Using the identity $(a-b)(a+b) = a^2 - b^2$:

$h = \frac{1.6(\sqrt{3} + 1)}{3 - 1}$

$h = \frac{1.6(\sqrt{3} + 1)}{2}$

$h = 0.8(\sqrt{3} + 1)$

Using $\sqrt{3} \approx 1.732$:

$h = 0.8(1.732 + 1) = 0.8(2.732) = 2.1856$ m.

Final Answer: The height of the pedestal is $0.8(\sqrt{3} + 1)$ m or approximately $2.186$ m.

Solution:

Given:

  • The distance from the foot of the tower to the point on the ground ($BC$) = $30$ m.
  • The angle of elevation of the top of the tower from the point on the ground ($\angle ACB$) = $30^\circ$.

To Find:

  • The height of the tower ($AB$).
30 m h C B A 30°

Step 1: Defining the Variables and Assumptions

Let $AB$ be the tower of height $h$ meters. Let $C$ be the point on the ground at a distance of $30$ m from the foot of the tower $B$. Thus, $BC = 30$ m. The angle of elevation $\angle ACB = 30^\circ$. We assume the tower stands vertically on the ground, making $\triangle ABC$ a right-angled triangle at $B$.

Step 2: Selecting the Trigonometric Ratio

In the right-angled triangle $\triangle ABC$, we have the side adjacent to the angle $\angle C$ (which is $BC$) and we need to find the side opposite to the angle $\angle C$ (which is $AB$). The trigonometric ratio that relates the opposite side and the adjacent side is the tangent function:

$\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{AB}{BC}$

Step 3: Substituting the Values

Substitute $\theta = 30^\circ$, $BC = 30$ m, and $AB = h$ into the formula:

$\tan(30^\circ) = \frac{h}{30}$

Step 4: Solving for $h$

We know from trigonometric standard values that $\tan(30^\circ) = \frac{1}{\sqrt{3}}$.

$\frac{1}{\sqrt{3}} = \frac{h}{30}$

Multiply both sides by $30$ to isolate $h$:

$h = \frac{30}{\sqrt{3}}$

Step 5: Rationalizing the Denominator

To simplify the expression, multiply the numerator and the denominator by $\sqrt{3}$:

$h = \frac{30}{\sqrt{3}} \times \frac{\sqrt{3}}{\sqrt{3}}$

$h = \frac{30\sqrt{3}}{3}$

$h = 10\sqrt{3}$

Step 6: Final Calculation

Using the approximate value of $\sqrt{3} \approx 1.732$:

$h = 10 \times 1.732 = 17.32$ m

Final Answer: The height of the tower is $10\sqrt{3}$ m or approximately $17.32$ m.

Solution:

Given:

  • Height of the building ($BC$) = $20$ m.
  • The transmission tower ($CD$) is fixed on top of the building.
  • Angle of elevation from a point $A$ on the ground to the bottom of the tower (point $C$) = $45^\circ$.
  • Angle of elevation from point $A$ on the ground to the top of the tower (point $D$) = $60^\circ$.

To find:

The height of the transmission tower ($h = CD$).

A B C D 45° 60° 20m h

Step 1: Define variables and identify triangles.

Let $AB = x$ be the distance from the point on the ground to the base of the building. Let $CD = h$ be the height of the tower. The total height of the building and tower is $BD = BC + CD = 20 + h$.

Step 2: Analyze $\triangle ABC$ (Right-angled at $B$).

In $\triangle ABC$, the angle of elevation $\angle BAC = 45^\circ$.

Using the trigonometric ratio: $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$

$\tan(45^\circ) = \frac{BC}{AB}$

Since $\tan(45^\circ) = 1$ [Trigonometric table value]:

$1 = \frac{20}{x}$

$x = 20$ m [Equation 1]

Step 3: Analyze $\triangle ABD$ (Right-angled at $B$).

In $\triangle ABD$, the angle of elevation $\angle BAD = 60^\circ$.

$\tan(60^\circ) = \frac{BD}{AB}$

Since $\tan(60^\circ) = \sqrt{3}$ [Trigonometric table value]:

$\sqrt{3} = \frac{20 + h}{x}$

Step 4: Solve for $h$.

Substitute $x = 20$ from Equation 1 into the equation from Step 3:

$\sqrt{3} = \frac{20 + h}{20}$

$20\sqrt{3} = 20 + h$ [Multiplying both sides by 20]

$h = 20\sqrt{3} - 20$

$h = 20(\sqrt{3} - 1)$

Using $\sqrt{3} \approx 1.732$:

$h = 20(1.732 - 1)$

$h = 20(0.732)$

$h = 14.64$ m

Final Answer: The height of the transmission tower is $20(\sqrt{3} - 1)$ m or approximately $14.64$ m.

Solution:

Given:

  • Height of the girl ($h_g$) = $1.2$ m.
  • Height of the balloon from the ground ($H$) = $88.2$ m.
  • Initial angle of elevation ($\theta_1$) = $60^\circ$.
  • Final angle of elevation ($\theta_2$) = $30^\circ$.

To Find:

The distance travelled by the balloon during the interval, let this be $d$.

A B C D 60° 30°

Step 1: Determine the effective height of the balloon from the girl's eye level.

Since the girl is $1.2$ m tall, the height of the balloon from her eye level ($h$) is the total height minus the girl's height.

$h = 88.2\text{ m} - 1.2\text{ m} = 87\text{ m}$.

Step 2: Analyze the first position of the balloon (Triangle 1).

Let the first position of the balloon be $C$ and the girl's eye position be $E$. Let the point on the ground directly below the balloon be $F$.

In the right-angled triangle formed by the eye level, the balloon, and the vertical line:

$\tan(60^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{h}{x_1}$

$\sqrt{3} = \frac{87}{x_1}$

$x_1 = \frac{87}{\sqrt{3}} = \frac{87\sqrt{3}}{3} = 29\sqrt{3}\text{ m}$.

Step 3: Analyze the second position of the balloon (Triangle 2).

Let the second position of the balloon be $D$.

In the right-angled triangle formed by the eye level, the new balloon position, and the vertical line:

$\tan(30^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{h}{x_2}$

$\frac{1}{\sqrt{3}} = \frac{87}{x_2}$

$x_2 = 87\sqrt{3}\text{ m}$.

Step 4: Calculate the distance travelled by the balloon.

The distance travelled ($d$) is the difference between the two horizontal distances $x_2$ and $x_1$.

$d = x_2 - x_1$

$d = 87\sqrt{3} - 29\sqrt{3}$

$d = (87 - 29)\sqrt{3}$

$d = 58\sqrt{3}\text{ m}$.

Using the approximation $\sqrt{3} \approx 1.732$:

$d = 58 \times 1.732 = 100.456\text{ m}$.

Final Answer: The distance travelled by the balloon is $58\sqrt{3}$ m (or approximately $100.46$ m).

Solution:

Given:

  • Height of the lighthouse ($AB$) = $75$ m.
  • Angle of depression of the first ship ($C$) = $45^\circ$.
  • Angle of depression of the second ship ($D$) = $30^\circ$.
  • The ships are on the same side of the lighthouse and lie on the same straight line.

To Find:

The distance between the two ships, i.e., the length of segment $CD$.

75m A B C D 45° 30°

Step 1: Defining Variables and Geometric Relationships

Let $AB$ be the lighthouse of height $75$ m. Let $C$ and $D$ be the positions of the two ships. Since the angles of depression are $45^\circ$ and $30^\circ$, the angles of elevation from the ships to the top of the lighthouse are also $45^\circ$ and $30^\circ$ respectively [By the property of alternate interior angles].

Let $BC = x$ and $BD = y$. The distance between the ships is $CD = y - x$.

Step 2: Calculating distance $BC$ in $\triangle ABC$

In right-angled triangle $\triangle ABC$:

$\tan(45^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{AB}{BC}$

We know $\tan(45^\circ) = 1$ and $AB = 75$ m.

$1 = \frac{75}{x}$

$x = 75$ m

Step 3: Calculating distance $BD$ in $\triangle ABD$

In right-angled triangle $\triangle ABD$:

$\tan(30^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{AB}{BD}$

We know $\tan(30^\circ) = \frac{1}{\sqrt{3}}$ and $AB = 75$ m.

$\frac{1}{\sqrt{3}} = \frac{75}{y}$

$y = 75\sqrt{3}$ m

Step 4: Finding the distance between the ships ($CD$)

The distance between the two ships is $CD = BD - BC$.

$CD = y - x$

$CD = 75\sqrt{3} - 75$

$CD = 75(\sqrt{3} - 1)$

Using the approximation $\sqrt{3} \approx 1.732$:

$CD = 75(1.732 - 1)$

$CD = 75(0.732)$

$CD = 54.9$ m

Final Answer: The distance between the two ships is $75(\sqrt{3} - 1)$ m or approximately $54.9$ m.

Solution:

Given:

1. Height of the building ($AB$) = $7$ m.

2. Angle of elevation of the top of the tower ($EC$) from the top of the building ($A$) = $60^\circ$.

3. Angle of depression of the foot of the tower ($D$) from the top of the building ($A$) = $45^\circ$.

To find:

The total height of the cable tower ($CD$).

7m A B C D 60° 45°

Step 1: Define the variables and geometric relationships.

Let $AB$ be the building of height $7$ m. Let $CD$ be the cable tower. Let $A$ be the top of the building and $B$ be its foot. Let $C$ be the top of the tower and $D$ be its foot. Let $E$ be a point on $CD$ such that $AE$ is horizontal. Thus, $AE = BD$ and $ED = AB = 7$ m.

Step 2: Analyze triangle $\triangle ABD$.

In the right-angled triangle $\triangle ABD$, the angle of depression from $A$ to $D$ is $45^\circ$. Therefore, the angle of elevation from $D$ to $A$ is also $45^\circ$ (alternate interior angles).

Using the trigonometric ratio tangent:

$\tan(45^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{AB}{BD}$

Since $\tan(45^\circ) = 1$:

$1 = \frac{7}{BD}$

$BD = 7$ m

[Since $AE$ is parallel to $BD$, $AE = BD = 7$ m].

Step 3: Analyze triangle $\triangle AEC$.

In the right-angled triangle $\triangle AEC$, the angle of elevation is $60^\circ$.

$\tan(60^\circ) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{CE}{AE}$

We know $\tan(60^\circ) = \sqrt{3}$ and $AE = 7$ m:

$\sqrt{3} = \frac{CE}{7}$

$CE = 7\sqrt{3}$ m

Step 4: Calculate the total height of the tower.

The total height of the tower $CD = CE + ED$.

We know $ED = AB = 7$ m.

$CD = 7\sqrt{3} + 7$

$CD = 7(\sqrt{3} + 1)$ m

Using the approximation $\sqrt{3} \approx 1.732$:

$CD \approx 7(1.732 + 1) = 7(2.732) = 19.124$ m.

Final Answer: The height of the tower is $7(\sqrt{3} + 1)$ m or approximately $19.12$ m.

Solution:

Given:

A TV tower $AB$ stands vertically on the bank of a canal. Let $BC$ be the width of the canal. From a point $C$ on the other bank, the angle of elevation of the top of the tower $A$ is $60^\circ$. From another point $D$, which is $20\text{ m}$ away from $C$ on the line joining $C$ to the foot of the tower $B$, the angle of elevation of the top of the tower $A$ is $30^\circ$.

To Find:

1. The height of the tower ($h = AB$).

2. The width of the canal ($x = BC$).

A B C D 60° 30° 20 m

Step 1: Defining Variables and Assumptions

Let the height of the tower $AB = h$ meters.

Let the width of the canal $BC = x$ meters.

The distance $BD = BC + CD = x + 20$ meters.

Step 2: Analyzing Triangle ABC

In the right-angled triangle $\triangle ABC$, the angle of elevation at $C$ is $60^\circ$.

Using the trigonometric ratio $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$:

$\tan(60^\circ) = \frac{AB}{BC}$

Since $\tan(60^\circ) = \sqrt{3}$:

$\sqrt{3} = \frac{h}{x}$

$h = x\sqrt{3}$ --- (Equation 1)

Step 3: Analyzing Triangle ABD

In the right-angled triangle $\triangle ABD$, the angle of elevation at $D$ is $30^\circ$.

Using the trigonometric ratio $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$:

$\tan(30^\circ) = \frac{AB}{BD}$

Since $\tan(30^\circ) = \frac{1}{\sqrt{3}}$ and $BD = x + 20$:

$\frac{1}{\sqrt{3}} = \frac{h}{x + 20}$

$x + 20 = h\sqrt{3}$ --- (Equation 2)

Step 4: Solving the System of Equations

Substitute the value of $h$ from Equation 1 into Equation 2:

$x + 20 = (x\sqrt{3})\sqrt{3}$

$x + 20 = 3x$ [Since $\sqrt{3} \times \sqrt{3} = 3$]

$20 = 3x - x$

$20 = 2x$

$x = 10$

Thus, the width of the canal is $10\text{ m}$.

Step 5: Calculating the Height of the Tower

Substitute $x = 10$ back into Equation 1:

$h = 10\sqrt{3}$

Using $\sqrt{3} \approx 1.732$:

$h = 10 \times 1.732 = 17.32\text{ m}$

Final Answer: The height of the tower is $10\sqrt{3}\text{ m}$ (or approximately $17.32\text{ m}$) and the width of the canal is $10\text{ m}$.

Solution:

Given:

  • A tree breaks at a certain point, and the top touches the ground.
  • The angle of elevation of the top of the tree from the point where it touches the ground is $\theta = 30^\circ$.
  • The distance between the foot of the tree and the point where the top touches the ground is $BC = 8$ m.

To Find:

The total height of the tree ($H = AB + AC$, where $A$ is the top, $B$ is the foot, and $C$ is the point where the top touches the ground, with the break occurring at point $D$).

B C D 8 m 30°

Step 1: Define the variables and model the triangle.

Let the original tree be $AD$. Let it break at point $D$. The part $AD$ bends such that the top $A$ touches the ground at point $C$. Let $B$ be the foot of the tree. Thus, $BD$ is the vertical part remaining standing, and $DC$ is the broken part that touches the ground. The total height of the tree is $H = BD + DC$.

In the right-angled triangle $\triangle DBC$ (right-angled at $B$):

  • Base $BC = 8$ m
  • Angle $\angle DCB = 30^\circ$

Step 2: Calculate the height of the standing part ($BD$).

Using the trigonometric ratio for tangent: $\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}$

$\tan(30^\circ) = \frac{BD}{BC}$

Since $\tan(30^\circ) = \frac{1}{\sqrt{3}}$ [Standard trigonometric value]:

$\frac{1}{\sqrt{3}} = \frac{BD}{8}$

$BD = \frac{8}{\sqrt{3}}$ m

Step 3: Calculate the length of the broken part ($DC$).

Using the trigonometric ratio for cosine: $\cos(\theta) = \frac{\text{Adjacent}}{\text{Hypotenuse}}$

$\cos(30^\circ) = \frac{BC}{DC}$

Since $\cos(30^\circ) = \frac{\sqrt{3}}{2}$ [Standard trigonometric value]:

$\frac{\sqrt{3}}{2} = \frac{8}{DC}$

$DC = \frac{16}{\sqrt{3}}$ m

Step 4: Calculate the total height of the tree ($H$).

$H = BD + DC$

$H = \frac{8}{\sqrt{3}} + \frac{16}{\sqrt{3}}$

$H = \frac{24}{\sqrt{3}}$

Rationalizing the denominator by multiplying the numerator and denominator by $\sqrt{3}$:

$H = \frac{24 \times \sqrt{3}}{\sqrt{3} \times \sqrt{3}} = \frac{24\sqrt{3}}{3} = 8\sqrt{3}$ m

Using $\sqrt{3} \approx 1.732$:

$H = 8 \times 1.732 = 13.856$ m

Final Answer: The height of the tree is $8\sqrt{3}$ m (or approximately $13.86$ m).

This website uses cookies

We use cookies to improve user experience. Choose what cookies you allow us to use. You can read more about our Cookie Policy in our Privacy Policy

Accept All
Decline All