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CBSE - Class 10 Mathematics Coordinate geometry Worksheet

EXERCISE 7.2

1.
Find the ratio in which the line segment joining the points (– 3, 10) and (6, – 8) is divided by (– 1, 6).
2.
If (1, 2), (4, $y$), ($x$, 6) and (3, 5) are the vertices of a parallelogram taken in order, find $x$ and $y$.
3.
Find the coordinates of a point A, where AB is the diameter of a circle whose centre is (2, – 3) and B is (1, 4).
4.
If A and B are (– 2, – 2) and (2, – 4), respectively, find the coordinates of P such that AP = $\frac{3}{7}$ AB and P lies on the line segment AB.
5.
Find the area of a rhombus if its vertices are (3, 0), (4, 5), (– 1, 4) and (– 2, – 1) taken in order. [Hint : Area of a rhombus = $\frac{1}{2}$ (product of its diagonals)]
6.
Find the ratio in which the line segment joining A(1, – 5) and B(– 4, 5) is divided by the x-axis. Also find the coordinates of the point of division.
7.
Find the coordinates of the points which divide the line segment joining A(– 2, 2) and B(2, 8) into four equal parts.
8.
Find the coordinates of the points of trisection of the line segment joining (4, –1) and (–2, –3).
9.
Find the coordinates of the point which divides the join of (–1, 7) and (4, –3) in the ratio 2 : 3.
10.

To conduct Sports Day activities, in your rectangular shaped school ground ABCD, lines have been drawn with chalk powder at a distance of 1m each. 100 flower pots have been placed at a distance of 1m from each other along AD, as shown in Fig. 7.12. Niharika runs $\frac{1}{4}$th the distance AD on the 2nd line and posts a green flag. Preet runs $\frac{1}{5}$th the distance AD on the eighth line and posts a red flag. What is the distance between both the flags? If Rashmi has to post a blue flag exactly halfway between the line segment joining the two flags, where should she post her flag?

Worksheet Answers

Solution:

Given:

Let the two points be $A(-3, 10)$ and $B(6, -8)$. Let the point that divides the line segment $AB$ be $P(-1, 6)$.

To Find:

The ratio $m_1 : m_2$ in which the point $P$ divides the line segment $AB$.


A(-3, 10) P(-1, 6) B(6, -8) m₁ m₂

Step 1: Applying the Section Formula

The Section Formula states that if a point $P(x, y)$ divides the line segment joining $A(x_1, y_1)$ and $B(x_2, y_2)$ in the ratio $m_1 : m_2$, then the coordinates of $P$ are given by:

$x = \frac{m_1x_2 + m_2x_1}{m_1 + m_2}$ and $y = \frac{m_1y_2 + m_2y_1}{m_1 + m_2}$

Let the ratio be $k : 1$. Thus, $m_1 = k$ and $m_2 = 1$.

Step 2: Substituting the Given Values

Here, $(x_1, y_1) = (-3, 10)$, $(x_2, y_2) = (6, -8)$, and $(x, y) = (-1, 6)$.

Using the x-coordinate formula:

$-1 = \frac{k(6) + 1(-3)}{k + 1}$

Step 3: Solving for k

Multiply both sides by $(k + 1)$:

$-1(k + 1) = 6k - 3$

Expand the left side:

$-k - 1 = 6k - 3$

Rearrange the terms to isolate $k$:

$-1 + 3 = 6k + k$

$2 = 7k$

$k = \frac{2}{7}$

Step 4: Verification using the y-coordinate

To ensure consistency, we check the y-coordinate using $k = \frac{2}{7}$:

$y = \frac{k(y_2) + 1(y_1)}{k + 1} = \frac{\frac{2}{7}(-8) + 1(10)}{\frac{2}{7} + 1}$

$y = \frac{-\frac{16}{7} + 10}{\frac{2+7}{7}} = \frac{\frac{-16 + 70}{7}}{\frac{9}{7}}$

$y = \frac{54}{7} \times \frac{7}{9} = \frac{54}{9} = 6$

Since the calculated y-coordinate matches the given y-coordinate of point $P$, the ratio is correct.

Final Answer: The point (-1, 6) divides the line segment joining (-3, 10) and (6, -8) in the ratio 2 : 7.

Solution:

Given: The vertices of a parallelogram taken in order are $A(1, 2)$, $B(4, y)$, $C(x, 6)$, and $D(3, 5)$.

To find: The values of $x$ and $y$.

A(1, 2) B(4, y) C(x, 6) D(3, 5)

Step 1: Understanding the Property of a Parallelogram
A fundamental property of a parallelogram is that its diagonals bisect each other. This means that the midpoint of diagonal $AC$ is the same as the midpoint of diagonal $BD$.

Step 2: Applying the Midpoint Formula
The midpoint $M$ of a line segment with endpoints $(x_1, y_1)$ and $(x_2, y_2)$ is given by the formula:
$M = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right)$

Step 3: Calculating the Midpoint of Diagonal $AC$
For $A(1, 2)$ and $C(x, 6)$:
Midpoint of $AC = \left( \frac{1 + x}{2}, \frac{2 + 6}{2} \right) = \left( \frac{1 + x}{2}, \frac{8}{2} \right) = \left( \frac{1 + x}{2}, 4 \right)$

Step 4: Calculating the Midpoint of Diagonal $BD$
For $B(4, y)$ and $D(3, 5)$:
Midpoint of $BD = \left( \frac{4 + 3}{2}, \frac{y + 5}{2} \right) = \left( \frac{7}{2}, \frac{y + 5}{2} \right)$

Step 5: Equating the Midpoints
Since the diagonals bisect each other, the midpoints must be equal:
$\left( \frac{1 + x}{2}, 4 \right) = \left( \frac{7}{2}, \frac{y + 5}{2} \right)$

Step 6: Solving for $x$
Equating the x-coordinates:
$\frac{1 + x}{2} = \frac{7}{2}$
Multiplying both sides by $2$:
$1 + x = 7$
$x = 7 - 1$
$x = 6$

Step 7: Solving for $y$
Equating the y-coordinates:
$4 = \frac{y + 5}{2}$
Multiplying both sides by $2$:
$8 = y + 5$
$y = 8 - 5$
$y = 3$

Final Answer: $x = 6$ and $y = 3$

Solution:

Given:

1. A circle with center $O$ at coordinates $(2, -3)$.

2. $AB$ is the diameter of the circle.

3. The coordinates of point $B$ are $(1, 4)$.

To Find:

The coordinates of point $A$, let us denote them as $(x, y)$.


O(2, -3) A(x, y) B(1, 4)

Step 1: Theoretical Basis

In a circle, the center $O$ is the midpoint of any diameter $AB$. According to the Midpoint Formula, if a line segment has endpoints $(x_1, y_1)$ and $(x_2, y_2)$, the midpoint $(x_m, y_m)$ is given by:

$x_m = \frac{x_1 + x_2}{2}$

$y_m = \frac{y_1 + y_2}{2}$


Step 2: Assigning Variables

Let the coordinates of point $A$ be $(x, y)$.

Let the coordinates of point $B$ be $(x_2, y_2) = (1, 4)$.

Let the coordinates of the center $O$ be $(x_m, y_m) = (2, -3)$.


Step 3: Calculating the x-coordinate of A

Using the midpoint formula for the x-coordinate:

$2 = \frac{x + 1}{2}$

[Multiplying both sides by 2]

$4 = x + 1$

[Subtracting 1 from both sides]

$x = 4 - 1$

$x = 3$


Step 4: Calculating the y-coordinate of A

Using the midpoint formula for the y-coordinate:

$-3 = \frac{y + 4}{2}$

[Multiplying both sides by 2]

$-6 = y + 4$

[Subtracting 4 from both sides]

$y = -6 - 4$

$y = -10$


Final Answer: The coordinates of point A are (3, -10).

Solution:

Given:

The coordinates of point $A$ are $(x_1, y_1) = (-2, -2)$.

The coordinates of point $B$ are $(x_2, y_2) = (2, -4)$.

Point $P(x, y)$ lies on the line segment $AB$ such that $AP = \frac{3}{7} AB$.

To find:

The coordinates of point $P(x, y)$.

A(-2, -2) P(x, y) B(2, -4) 3 parts 4 parts

Step 1: Determining the ratio $AP : PB$

We are given $AP = \frac{3}{7} AB$.

Since $P$ lies on $AB$, we can write $AB = AP + PB$.

Substituting the given relation into the equation:

$AP = \frac{3}{7} (AP + PB)$

$7 AP = 3 AP + 3 PB$ [Multiplying both sides by 7]

$7 AP - 3 AP = 3 PB$ [Transposing $3 AP$ to the left side]

$4 AP = 3 PB$

$\frac{AP}{PB} = \frac{3}{4}$

Thus, point $P$ divides the line segment $AB$ in the ratio $m : n = 3 : 4$.

Step 2: Applying the Section Formula

The Section Formula states that the coordinates of a point $P(x, y)$ dividing the line segment joining $A(x_1, y_1)$ and $B(x_2, y_2)$ in the ratio $m : n$ are given by:

$x = \frac{mx_2 + nx_1}{m + n}$

$y = \frac{my_2 + ny_1}{m + n}$

Step 3: Calculating the x-coordinate

$x = \frac{3(2) + 4(-2)}{3 + 4}$

$x = \frac{6 - 8}{7}$

$x = -\frac{2}{7}$

Step 4: Calculating the y-coordinate

$y = \frac{3(-4) + 4(-2)}{3 + 4}$

$y = \frac{-12 - 8}{7}$

$y = -\frac{20}{7}$

Conclusion:

The coordinates of point $P$ are $(-\frac{2}{7}, -\frac{20}{7})$.

Final Answer: The coordinates of point P are $\left(-\frac{2}{7}, -\frac{20}{7}\right)$.

Solution:

Given: The vertices of a rhombus taken in order are $A(3, 0)$, $B(4, 5)$, $C(-1, 4)$, and $D(-2, -1)$.

To Find: The area of the rhombus $ABCD$.

A(3, 0) B(4, 5) C(-1, 4) D(-2, -1)

Formula Used: The distance $d$ between two points $(x_1, y_1)$ and $(x_2, y_2)$ is given by the Distance Formula: $d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$. The area of a rhombus is given by $\text{Area} = \frac{1}{2} \times d_1 \times d_2$, where $d_1$ and $d_2$ are the lengths of the diagonals.

Step 1: Calculate the length of diagonal $AC$ ($d_1$).
The vertices are $A(3, 0)$ and $C(-1, 4)$.
$d_1 = \sqrt{(-1 - 3)^2 + (4 - 0)^2}$ [Substituting coordinates into the distance formula]
$d_1 = \sqrt{(-4)^2 + (4)^2}$
$d_1 = \sqrt{16 + 16}$
$d_1 = \sqrt{32} = 4\sqrt{2}$ units.

Step 2: Calculate the length of diagonal $BD$ ($d_2$).
The vertices are $B(4, 5)$ and $D(-2, -1)$.
$d_2 = \sqrt{(-2 - 4)^2 + (-1 - 5)^2}$ [Substituting coordinates into the distance formula]
$d_2 = \sqrt{(-6)^2 + (-6)^2}$
$d_2 = \sqrt{36 + 36}$
$d_2 = \sqrt{72} = 6\sqrt{2}$ units.

Step 3: Calculate the area of the rhombus.
$\text{Area} = \frac{1}{2} \times d_1 \times d_2$
$\text{Area} = \frac{1}{2} \times (4\sqrt{2}) \times (6\sqrt{2})$ [Substituting the values of $d_1$ and $d_2$]
$\text{Area} = \frac{1}{2} \times 24 \times (\sqrt{2} \times \sqrt{2})$
$\text{Area} = \frac{1}{2} \times 24 \times 2$
$\text{Area} = 24$ square units.

Final Answer: The area of the rhombus is 24 square units.

Solution:

Given:
The coordinates of the endpoints of the line segment are $A(x_1, y_1) = (1, -5)$ and $B(x_2, y_2) = (-4, 5)$.
The line segment $AB$ is divided by the $x$-axis.

To Find:
1. The ratio ($k:1$) in which the $x$-axis divides the line segment $AB$.
2. The coordinates of the point of division ($P$).

A(1, -5) B(-4, 5) P(x, 0)

Step 1: Defining the Point of Division
Let the point $P$ on the $x$-axis divide the line segment $AB$ in the ratio $k:1$.
Since the point $P$ lies on the $x$-axis, its $y$-coordinate must be $0$. Therefore, the coordinates of $P$ are $(x, 0)$.

Step 2: Applying the Section Formula
The Section Formula states that if a point $P(x, y)$ divides the line segment joining $A(x_1, y_1)$ and $B(x_2, y_2)$ in the ratio $m:n$, then:
$x = \frac{mx_2 + nx_1}{m+n}$ and $y = \frac{my_2 + ny_1}{m+n}$

Substituting our values ($m=k, n=1, x_1=1, y_1=-5, x_2=-4, y_2=5$):
$y = \frac{k(5) + 1(-5)}{k+1}$

Step 3: Solving for the Ratio $k$
Since the point lies on the $x$-axis, $y = 0$.
$0 = \frac{5k - 5}{k+1}$
Multiplying both sides by $(k+1)$ (assuming $k \neq -1$):
$0 = 5k - 5$
$5k = 5$
$k = \frac{5}{5} = 1$
Thus, the ratio $k:1$ is $1:1$.

Step 4: Finding the Coordinates of the Point of Division
Now, substitute $k=1$ into the formula for the $x$-coordinate:
$x = \frac{k(x_2) + 1(x_1)}{k+1}$
$x = \frac{1(-4) + 1(1)}{1+1}$
$x = \frac{-4 + 1}{2}$
$x = \frac{-3}{2} = -1.5$

The coordinates of the point of division $P$ are $(x, y) = \left(-\frac{3}{2}, 0\right)$.

Final Answer: The line segment is divided by the x-axis in the ratio 1:1, and the coordinates of the point of division are (-1.5, 0).

Solution:

Given: The coordinates of the endpoints of the line segment are $A(-2, 2)$ and $B(2, 8)$.

To Find: The coordinates of the three points $P$, $Q$, and $R$ that divide the line segment $AB$ into four equal parts.

A(-2, 2) P Q R B(2, 8)

Theoretical Basis: The Section Formula states that the coordinates of a point $P(x, y)$ dividing the line segment joining $A(x_1, y_1)$ and $B(x_2, y_2)$ in the ratio $m:n$ are given by:

$x = \frac{mx_2 + nx_1}{m+n}$, $y = \frac{my_2 + ny_1}{m+n}$

Step 1: Finding point Q (The Midpoint of AB)

Since $Q$ divides $AB$ into four equal parts, $Q$ is the midpoint of $AB$. The ratio is $1:1$.

$x_Q = \frac{-2 + 2}{2} = \frac{0}{2} = 0$

$y_Q = \frac{2 + 8}{2} = \frac{10}{2} = 5$

Thus, $Q = (0, 5)$.

Step 2: Finding point P (The Midpoint of AQ)

Point $P$ is the midpoint of the segment $AQ$, where $A = (-2, 2)$ and $Q = (0, 5)$.

$x_P = \frac{-2 + 0}{2} = \frac{-2}{2} = -1$

$y_P = \frac{2 + 5}{2} = \frac{7}{2} = 3.5$

Thus, $P = (-1, 3.5)$.

Step 3: Finding point R (The Midpoint of QB)

Point $R$ is the midpoint of the segment $QB$, where $Q = (0, 5)$ and $B = (2, 8)$.

$x_R = \frac{0 + 2}{2} = \frac{2}{2} = 1$

$y_R = \frac{5 + 8}{2} = \frac{13}{2} = 6.5$

Thus, $R = (1, 6.5)$.

Conclusion: The points dividing the line segment $AB$ into four equal parts are $P(-1, 3.5)$, $Q(0, 5)$, and $R(1, 6.5)$.

Final Answer: The coordinates of the points are $(-1, 3.5)$, $(0, 5)$, and $(1, 6.5)$.

Solution:

Given: A line segment joining the points $A(4, -1)$ and $B(-2, -3)$.

To Find: The coordinates of the two points of trisection of the line segment $AB$.

A(4, -1) P Q B(-2, -3)

Step 1: Understanding Trisection
Trisection means dividing the line segment into three equal parts. Let the points of trisection be $P$ and $Q$. Thus, $AP = PQ = QB$.
Point $P$ divides $AB$ in the ratio $1:2$.
Point $Q$ divides $AB$ in the ratio $2:1$.

Step 2: Applying the Section Formula
The section formula states that the coordinates of a point dividing a line segment joining $(x_1, y_1)$ and $(x_2, y_2)$ in the ratio $m:n$ are given by:
$x = \frac{mx_2 + nx_1}{m+n}$, $y = \frac{my_2 + ny_1}{m+n}$

Step 3: Finding Coordinates of Point P
For point $P$, $m=1$ and $n=2$. The coordinates are $(x_1, y_1) = (4, -1)$ and $(x_2, y_2) = (-2, -3)$.
$x_P = \frac{1(-2) + 2(4)}{1+2} = \frac{-2 + 8}{3} = \frac{6}{3} = 2$
$y_P = \frac{1(-3) + 2(-1)}{1+2} = \frac{-3 - 2}{3} = -\frac{5}{3}$
So, $P = (2, -\frac{5}{3})$.

Step 4: Finding Coordinates of Point Q
For point $Q$, $m=2$ and $n=1$. The coordinates are $(x_1, y_1) = (4, -1)$ and $(x_2, y_2) = (-2, -3)$.
$x_Q = \frac{2(-2) + 1(4)}{2+1} = \frac{-4 + 4}{3} = \frac{0}{3} = 0$
$y_Q = \frac{2(-3) + 1(-1)}{2+1} = \frac{-6 - 1}{3} = -\frac{7}{3}$
So, $Q = (0, -\frac{7}{3})$.

Final Answer: The coordinates of the points of trisection are $(2, -\frac{5}{3})$ and $(0, -\frac{7}{3})$.

Solution:

Given:
The coordinates of two points are $A(x_1, y_1) = (-1, 7)$ and $B(x_2, y_2) = (4, -3)$.
The ratio in which the point divides the line segment $AB$ is $m : n = 2 : 3$.

To Find:
The coordinates of the point $P(x, y)$ that divides the line segment joining $A$ and $B$ in the ratio $2 : 3$.

A(-1, 7) B(4, -3) P(x, y) 2 3

Step 1: Applying the Section Formula
The Section Formula states that the coordinates of a point $P(x, y)$ dividing the line segment joining points $(x_1, y_1)$ and $(x_2, y_2)$ internally in the ratio $m : n$ are given by:
$x = \frac{mx_2 + nx_1}{m + n}$
$y = \frac{my_2 + ny_1}{m + n}$

Step 2: Identifying the variables
From the given information:
$x_1 = -1, y_1 = 7$
$x_2 = 4, y_2 = -3$
$m = 2, n = 3$

Step 3: Calculating the x-coordinate
Substituting the values into the formula for $x$:
$x = \frac{(2)(4) + (3)(-1)}{2 + 3}$
$x = \frac{8 - 3}{5}$ [Performing multiplication and addition]
$x = \frac{5}{5}$
$x = 1$

Step 4: Calculating the y-coordinate
Substituting the values into the formula for $y$:
$y = \frac{(2)(-3) + (3)(7)}{2 + 3}$
$y = \frac{-6 + 21}{5}$ [Performing multiplication and addition]
$y = \frac{15}{5}$
$y = 3$

Final Answer:
The coordinates of the point which divides the join of (-1, 7) and (4, -3) in the ratio 2 : 3 are (1, 3).

Solution:

Given:

1. The school ground is rectangular, represented by a coordinate plane where the x-axis represents the lines (1 to 10) and the y-axis represents the distance along AD (in meters).

2. Total distance along AD = $100$ meters (since there are 100 flower pots placed 1m apart).

3. Niharika runs on the 2nd line ($x_1 = 2$) and covers $\frac{1}{4}$ of the distance AD.

4. Preet runs on the 8th line ($x_2 = 8$) and covers $\frac{1}{5}$ of the distance AD.

To Find:

1. The distance between the green flag (Niharika) and the red flag (Preet).

2. The coordinates where Rashmi should post her blue flag (the midpoint of the two flags).

A(0,0) B D(0,100) Green Flag (2, 25) Red Flag (8, 20)

Step 1: Determine the coordinates of the flags.

Let the position of the green flag be $G(x_1, y_1)$.

$x_1 = 2$

$y_1 = \frac{1}{4} \times 100 = 25$

So, $G = (2, 25)$.

Let the position of the red flag be $R(x_2, y_2)$.

$x_2 = 8$

$y_2 = \frac{1}{5} \times 100 = 20$

So, $R = (8, 20)$.

Step 2: Calculate the distance between the two flags.

Using the Distance Formula: $d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$

$d = \sqrt{(8 - 2)^2 + (20 - 25)^2}$

$d = \sqrt{(6)^2 + (-5)^2}$

$d = \sqrt{36 + 25}$

$d = \sqrt{61}$

$d \approx 7.81$ meters.

Step 3: Determine the position of the blue flag.

The blue flag is at the midpoint $M(x, y)$ of the line segment joining $G(2, 25)$ and $R(8, 20)$.

Using the Midpoint Formula: $M = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right)$

$x = \frac{2 + 8}{2} = \frac{10}{2} = 5$

$y = \frac{25 + 20}{2} = \frac{45}{2} = 22.5$

Therefore, the blue flag should be posted on the 5th line at a distance of 22.5 meters from AD.

Final Answer: The distance between the two flags is $\sqrt{61}$ m (approx 7.81 m). Rashmi should post her blue flag at the coordinates (5, 22.5).

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