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CBSE - Class 11 Mathematics Conic Sections Worksheet

1.
In each of the Exercises 1 to 6, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
3. 9$y^2$ – 4$x^2$ = 36
2.

Oil India went ex-bonus (1:2) on Mar 27th 2018. What does that mean for an investory who holds 100 shares of OIL?  

hint: if you got this question wrong, this would be a good opportunity to learn how the bonus shares work. A simple Google search would reveal that but if you have doubts, VRD sir will explain.

a.

He will now have 200 shares (i.e. 100 shares extra)

b.

He will now have 150 shares (i.e. 50 shares extra)

c.

He will now have 300 shares (i.e. 200 shares extra)

d.

He will now have 50 shares (i.e. reduced by 50 shares)

3.
In each of the Exercises 1 to 6, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
4. 16$x^2$ – 9$y^2$ = 576
4.
In each of the following Exercises 10 to 20, find the equation for the ellipse that satisfies the given conditions:
12. Vertices (± 6, 0), foci (± 4, 0)
5.

Find the equation of the circle with 5. centre (–$a$, –$b$) and radius $sqrt{a^2-b^2}$.

6.

Does Zerodha allow intraday trading in F&O of stocks that have gone into the ban period (assuming you don't have an existing position)? 

a.

Yes

b.

No

c.

Depending on account balance

d.

Depending on whether you have the account approval

7.

For an IPO, which of these numbers is relatively easy to manipulate (by operators or the IPO managers)?

a.

Retail participation

b.

Institutional participation

8.
In each of the following Exercises 1 to 6, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
2. $x^2$ = 6$y$
9.
In each of the Exercises 7 to 12, find the equation of the parabola that satisfies the given conditions:
7. Focus (6,0); directrix $x$ = – 6
10.

Based on our IPO swing trading strategy, do you think we had a trade in Lemon Tree?

a.

Yes

b.

No

11.

This is a daily chart of Gitanjali Gems, which was tangled in controvery of Nirav Modi /PNB scam. This is a classic example of ...

a.

when one should be greedy when others are fearful

b.

Excessive fear playing out in the market

c.

A falling knife

12.
In each of the Exercises 1 to 9, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
1. $frac{x^2}{36} + $frac{y^2}{16} = 1$
13.
The cable of a uniformly loaded suspension bridge hangs in the form of a parabola. The roadway which is horizontal and 100 m long is supported by vertical wires attached to the cable, the longest wire being 30 m and the shortest being 6 m. Find the length of a supporting wire attached to the roadway 18 m from the middle.
14.

For an IPO which of these is a must-have for an intraday trading opportunity? (pick one)

a.

Listing gains

b.

Substantial grey market premium/Kostak rate

c.

Liquidity

d.

Short covering

15.
In each of the Exercises 1 to 6, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
5. 5$y^2$ – 9$x^2$ = 36
16.

On the day of listing, especially the listing where the listing gains are high, it is a good strategy to short in the first mins of listing itself because people will start booking profits and it will become harder to chase the decline.

a. True b. False
17.
In each of the following Exercises 10 to 20, find the equation for the ellipse that satisfies the given conditions:
14. Ends of major axis (0, ±$sqrt{5}$ ), ends of minor axis (± 1, 0)
18.
Does the point (–2.5, 3.5) lie inside, outside or on the circle $x^2$ + $y^2$ = 25?
19.
In each of the Exercises 7 to 15, find the equations of the hyperbola satisfying the given conditions.
11. Foci (0, ±13), the conjugate axis is of length 24.
20.

This is a query posted on a trading forum. What do you know that this individual doesn't (pick 2options) :

"Please suggest should I buy PNB put option of next month expiry becz next month quarterly result announcment is there .It is possible that big drop in net profit and huge rise in NPA declared… This will drag stock below 85"

a.

No one knows how the next monthly quarterly result will be. It may be good, bad or ugly!

b.

The current market price has already priced in (or discounted) all the available information so there is no additonal news that this individual or anyone can capitalize unless they have some insider news

c.

PNB does have a high chance of falling from the current levels

d.

There is limited risk of buying a put option so the risk rewards seems to be favorable 

Worksheet Answers

Solution:

Step 1: Standardizing the Hyperbola Equation

Given the equation: $9y^2 - 4x^2 = 36$

To convert this into the standard form of a hyperbola, divide both sides by $36$ [Per the algebraic axiom of equivalent division]:

$\frac{9y^2}{36} - \frac{4x^2}{36} = \frac{36}{36}$

$\frac{y^2}{4} - \frac{x^2}{9} = 1$

Comparing this to the standard form $\frac{y^2}{a^2} - \frac{x^2}{b^2} = 1$, we observe that the transverse axis is along the $y$-axis [Geometric property of vertical hyperbolas].

Step 2: Identifying Parameters $a$ and $b$

From the standard equation, we identify:

  • $a^2 = 4 \implies a = 2$
  • $b^2 = 9 \implies b = 3$

Step 3: Calculating Foci and Eccentricity

For a hyperbola $\frac{y^2}{a^2} - \frac{x^2}{b^2} = 1$, the relationship between parameters is defined by $c^2 = a^2 + b^2$ [Per the Pythagorean relation in hyperbolas].

$c^2 = 4 + 9 = 13 \implies c = \sqrt{13}$

Eccentricity ($e$):

$e = \frac{c}{a} = \frac{\sqrt{13}}{2}$

Foci Coordinates: $(0, \pm c) = (0, \pm \sqrt{13})$

Step 4: Determining Vertices and Latus Rectum

Vertices: $(0, \pm a) = (0, \pm 2)$

Length of Latus Rectum:

$L = \frac{2b^2}{a} = \frac{2(9)}{2} = 9$

O(0,0) V(0,2) V'(0,-2) F(0,√13)

Summary of Calculated Values

Parameter Result
Foci $(0, \pm \sqrt{13})$
Vertices $(0, \pm 2)$
Eccentricity $\frac{\sqrt{13}}{2}$
Length of Latus Rectum $9$

Final Solution: The foci are $(0, \pm \sqrt{13})$, the vertices are $(0, \pm 2)$, the eccentricity is $\frac{\sqrt{13}}{2}$, and the length of the latus rectum is $9$.

2.
Option B

Solution:

Step 1: Standardizing the Hyperbola Equation

Given the equation: $16x^2 - 9y^2 = 576$.

To convert this into the standard form of a hyperbola, $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$, we divide the entire equation by $576$:

$\frac{16x^2}{576} - \frac{9y^2}{576} = \frac{576}{576}$

$\frac{x^2}{36} - \frac{y^2}{64} = 1$ [By algebraic simplification]

Step 2: Identifying Parameters $a$ and $b$

Comparing the simplified equation with the standard form $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$:

  • $a^2 = 36 \implies a = 6$
  • $b^2 = 64 \implies b = 8$

Step 3: Calculating Eccentricity ($e$) and Foci ($c$)

For a hyperbola, the relationship between $a, b,$ and $c$ is given by $c^2 = a^2 + b^2$ [Per the definition of hyperbola focal distance]:

$c^2 = 36 + 64 = 100$

$c = \sqrt{100} = 10$

The eccentricity ($e$) is defined as $e = \frac{c}{a}$:

$e = \frac{10}{6} = \frac{5}{3}$

Step 4: Deriving Geometric Coordinates and Measurements

Since the $x^2$ term is positive, the transverse axis lies along the x-axis.

  • Vertices: $(\pm a, 0) = (\pm 6, 0)$
  • Foci: $(\pm c, 0) = (\pm 10, 0)$
  • Length of Latus Rectum: $LR = \frac{2b^2}{a}$ [Per standard conic formula]
  • $LR = \frac{2(64)}{6} = \frac{128}{6} = \frac{64}{3}$
F(10,0) F'(-10,0) V(6,0) V'(-6,0)

Summary of Results

Metric Calculated Value
Vertices $(\pm 6, 0)$
Foci $(\pm 10, 0)$
Eccentricity ($e$) $\frac{5}{3}$
Length of Latus Rectum $\frac{64}{3}$

Final Solution: The vertices are $(\pm 6, 0)$, the foci are $(\pm 10, 0)$, the eccentricity is $\frac{5}{3}$, and the length of the latus rectum is $\frac{64}{3}$ units.

Solution:

Step 1: Analyzing Given Parameters

The vertices are given as $(\pm 6, 0)$ and the foci are given as $(\pm 4, 0)$.
Since the $y$-coordinates are zero for both vertices and foci, the major axis of the ellipse lies along the $x$-axis. [Per standard conic form criteria].

Step 2: Identifying Constants $a$ and $c$

The standard form for an ellipse centered at the origin with the major axis along the $x$-axis is $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$, where $a > b$.

  • The vertices are $(\pm a, 0)$. Given $(\pm 6, 0)$, we determine $a = 6$. Thus, $a^2 = 36$.
  • The foci are $(\pm c, 0)$. Given $(\pm 4, 0)$, we determine $c = 4$. Thus, $c^2 = 16$.

Step 3: Calculating Parameter $b^2$

For any ellipse, the relationship between $a$, $b$, and $c$ is defined by the equation: $c^2 = a^2 - b^2$ [Derived from the focal property of ellipses].

Substituting the known values: $16 = 36 - b^2$ $b^2 = 36 - 16$ $b^2 = 20$

Step 4: Constructing the Equation

Substituting $a^2 = 36$ and $b^2 = 20$ into the standard equation $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$:

$\frac{x^2}{36} + \frac{y^2}{20} = 1$

Step 5: Visual Representation

V1(-6,0) V2(6,0) F1(-4,0) F2(4,0)

Final Solution: \frac{x^2}{36} + \frac{y^2}{20} = 1

Solution:

Step 1: Establishing the Standard Form of a Circle

The standard equation of a circle with a center at $(h, k)$ and a radius $r$ is given by the formula:

$(x - h)^2 + (y - k)^2 = r^2$

[Per the definition of a circle as the locus of points at a constant distance from a fixed point].

Step 2: Identifying Given Parameters

From the problem statement, we identify the following variables:

  • Center $(h, k) = (-a, -b)$
  • Radius $r = \sqrt{a^2 - b^2}$

Step 3: Substitution into the General Equation

Substituting the values of $h$, $k$, and $r$ into the standard form $(x - h)^2 + (y - k)^2 = r^2$:

$(x - (-a))^2 + (y - (-b))^2 = (\sqrt{a^2 - b^2})^2$

Step 4: Algebraic Simplification

Simplifying the signs and squaring the terms:

$(x + a)^2 + (y + b)^2 = a^2 - b^2$

Expanding the binomial squares using the algebraic identity $(m + n)^2 = m^2 + 2mn + n^2$ [Per the Binomial Theorem/Algebraic Expansion]:

$(x^2 + 2ax + a^2) + (y^2 + 2by + b^2) = a^2 - b^2$

Step 5: Final Rearrangement

Subtract $a^2$ from both sides and add $b^2$ to both sides to consolidate the equation:

$x^2 + 2ax + a^2 + y^2 + 2by + b^2 = a^2 - b^2$ $x^2 + y^2 + 2ax + 2by + b^2 + b^2 = 0$ $x^2 + y^2 + 2ax + 2by + 2b^2 = 0$

Visual Representation

Center (-a, -b) r

Final Solution: x^2 + y^2 + 2ax + 2by + 2b^2 = 0

6.
Option B

Solution:

According to NSE, intraday trading is allowed in futures and options of the stocks that are in F&O ban because intraday trading doesn't increase the open interest of the contract. Therefore, technically speaking, Zerodha should have allowed the intraday trades in these contracts.

However, because of their risk management policies, Zerodha doesn't allow intraday trading in derivatives of scripts that are in the ban period.

You should be aware of that if you use their platform.

7.
Option B

Solution:

Step 1: Identification of the Parabolic Form

The given equation is $x^2 = 6y$. This equation follows the standard form of a parabola that opens upwards, expressed as $x^2 = 4ay$, where $a > 0$. [By the standard definition of a parabola symmetric about the $y$-axis].

Step 2: Determining the Value of the Parameter $a$

Comparing $x^2 = 6y$ with the standard equation $x^2 = 4ay$:

$4a = 6$

$a = \frac{6}{4} = 1.5$

[By algebraic comparison of coefficients].

Step 3: Calculating Geometric Properties

  • Focus: For a parabola of the form $x^2 = 4ay$, the focus is located at $(0, a)$. Substituting $a = 1.5$, the focus is $(0, 1.5)$.
  • Axis of the Parabola: Since the variable $x$ is squared, the parabola is symmetric about the $y$-axis. Thus, the axis of the parabola is the $y$-axis, represented by the equation $x = 0$.
  • Equation of the Directrix: The directrix for this standard form is given by $y = -a$. Substituting $a = 1.5$, we get $y = -1.5$.
  • Length of the Latus Rectum: The length of the latus rectum is defined as $|4a|$. Given $4a = 6$, the length is $6$ units.

Step 4: Geometric Representation

Focus(0, 1.5) Directrix y = -1.5

Step 5: Summary Table of Results

Property Result
Focus $(0, 1.5)$
Axis $x = 0$ ($y$-axis)
Directrix $y = -1.5$
Length of Latus Rectum $6$ units

Final Solution: The coordinates of the focus are $(0, 1.5)$, the axis of the parabola is $x = 0$, the equation of the directrix is $y = -1.5$, and the length of the latus rectum is $6$ units.

Solution:

Step 1: Analyzing Geometric Properties

Given the focus $F$ at $(6, 0)$ and the directrix $d$ at $x = -6$, we observe the following:

  • The focus lies on the $x$-axis.
  • The directrix is a vertical line perpendicular to the $x$-axis.
  • Since the focus is $(a, 0)$ and the directrix is $x = -a$, the parabola is symmetric about the $x$-axis and opens towards the positive $x$-direction [Per the standard definition of a parabola].
  • Here, $a = 6$.

Step 2: Mathematical Derivation via Conic Definition

By definition, a parabola is the locus of a point $P(x, y)$ such that its distance from the focus $F(6, 0)$ equals its perpendicular distance from the directrix $x = -6$.

Distance $PF = \sqrt{(x - 6)^2 + (y - 0)^2}$

Distance $PD = |x - (-6)| = |x + 6|$

Equating the distances (since $PF = PD$):

$\sqrt{(x - 6)^2 + y^2} = |x + 6|$

Squaring both sides [Axiom of Equality]:

$(x - 6)^2 + y^2 = (x + 6)^2$

Step 3: Algebraic Expansion and Simplification

Expanding the binomial squares:

$x^2 - 12x + 36 + y^2 = x^2 + 12x + 36$

Subtracting $x^2$ and $36$ from both sides:

$-12x + y^2 = 12x$

Adding $12x$ to both sides:

$y^2 = 12x + 12x$

$y^2 = 24x$

Visual Representation

F(6, 0) x = -6

Final Solution: The equation of the parabola is $y^2 = 24x$.

10.
Option A
11.
Option C

Solution:

When a scandal like Nirav Modi/PNB happens, there is a strong urge among newcomers to look for bargain buying. They think that the stock will eventually bounce back to its previous levels but that is where they make mistake. You always have to stay away from companies where the promoters are alleged of fradulent activities - however low the stock prices go. A 100 rupee can cal look cheap after falling to 75 but remember that that 75 rupee stock can become a 5 rupee stock as well. Don't gamble with such cases.

Solution:

Step 1: Identifying the Standard Form

The given equation is $\frac{x^2}{36} + \frac{y^2}{16} = 1$. Comparing this with the standard equation of an ellipse $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$, where $a > b$, we identify that this is a horizontal ellipse centered at the origin $(0,0)$.

Given parameters:

  • $a^2 = 36 \implies a = 6$
  • $b^2 = 16 \implies b = 4$
[Per the Standard Equation of an Ellipse along the $x$-axis]

Step 2: Calculating Eccentricity ($e$)

The eccentricity of an ellipse is determined by the relationship $c^2 = a^2 - b^2$, where $c$ is the distance from the center to the foci.

$c^2 = 36 - 16 = 20$

$c = \sqrt{20} = 2\sqrt{5}$

The eccentricity $e$ is defined as $e = \frac{c}{a}$:

$e = \frac{2\sqrt{5}}{6} = \frac{\sqrt{5}}{3} \approx 0.745$

[By the definition of linear eccentricity in conic sections]

Step 3: Calculating Key Geometric Properties

ParameterFormulaCalculationResult
Foci$(\pm c, 0)$$(\pm 2\sqrt{5}, 0)$$(\pm 2\sqrt{5}, 0)$
Vertices$(\pm a, 0)$$(\pm 6, 0)$$(\pm 6, 0)$
Major Axis Length$2a$$2 \times 6$$12$ units
Minor Axis Length$2b$$2 \times 4$$8$ units
Latus Rectum Length$\frac{2b^2}{a}$$\frac{2 \times 16}{6}$$\frac{16}{3}$ units

Step 4: Visualization

Center (0,0) Vertex (6,0) Focus (2√5,0)

Final Solution: The foci are $(\pm 2\sqrt{5}, 0)$, the vertices are $(\pm 6, 0)$, the length of the major axis is $12$, the length of the minor axis is $8$, the eccentricity is $\frac{\sqrt{5}}{3}$, and the length of the latus rectum is $\frac{16}{3}$.

Solution:

Step 1: Setting up the Coordinate System

We represent the parabolic cable on a Cartesian plane. Let the vertex of the parabola be at $(0, 6)$ on the $y$-axis. Since the bridge is $100\text{ m}$ long, the supporting wires extend from $x = -50$ to $x = 50$. The longest wires at the ends have a length of $30\text{ m}$, meaning the points $(\pm 50, 30)$ lie on the parabola [Definition of a Parabola with Vertical Axis].

0 (-50, 30) (50, 30) (0, 6)

Step 2: Defining the Parabolic Equation

The standard equation of a parabola with vertex at $(0, h)$ opening upwards is $x^2 = 4a(y - k)$. Given the vertex $(0, 6)$, the equation becomes:

$x^2 = 4a(y - 6)$

To find the constant $4a$, we substitute the point $(50, 30)$ which satisfies the equation [Method of Undetermined Coefficients]:

$50^2 = 4a(30 - 6)$

$2500 = 4a(24)$

$4a = \frac{2500}{24} = \frac{625}{6}$

Step 3: Calculating the Length at $x = 18$

The equation of the cable is $x^2 = \frac{625}{6}(y - 6)$. We need to find $y$ when $x = 18$ meters from the middle:

$18^2 = \frac{625}{6}(y - 6)$

$324 = \frac{625}{6}(y - 6)$

Isolating $(y - 6)$:

$y - 6 = \frac{324 \times 6}{625}$

$y - 6 = \frac{1944}{625}$

$y - 6 = 3.1104$

$y = 6 + 3.1104$

$y = 9.1104\text{ m}$

Step 4: Verification of Results

Position ($x$) Cable Height ($y$)
$0$ $6$
$18$ $9.1104$
$50$ $30$

Final Solution: The length of the supporting wire attached to the roadway 18 m from the middle is 9.1104 m.

14.
Option C

Solution:

Step 1: Standardizing the Hyperbola Equation

Given the equation: $5y^2 - 9x^2 = 36$

To convert this into the standard form of a hyperbola, we divide the entire equation by $36$ [Algebraic Property of Equality]:

$\frac{5y^2}{36} - \frac{9x^2}{36} = \frac{36}{36}$

$\frac{y^2}{36/5} - \frac{x^2}{4} = 1$

This is of the standard form $\frac{y^2}{a^2} - \frac{x^2}{b^2} = 1$, which represents a hyperbola with its transverse axis along the $y$-axis [Standard Equation of a Hyperbola].

Step 2: Identifying Parameters $a$ and $b$

Comparing the given equation to the standard form:

  • $a^2 = \frac{36}{5} \implies a = \frac{6}{\sqrt{5}}$
  • $b^2 = 4 \implies b = 2$

Step 3: Calculating Eccentricity ($e$)

The relationship between $a, b,$ and $e$ for a hyperbola is defined as $c^2 = a^2 + b^2$ and $e = \frac{c}{a}$ [Geometric Definition of Hyperbola].

$c^2 = \frac{36}{5} + 4 = \frac{36 + 20}{5} = \frac{56}{5}$

$c = \sqrt{\frac{56}{5}} = \frac{2\sqrt{14}}{\sqrt{5}}$

$e = \frac{c}{a} = \frac{2\sqrt{14}/\sqrt{5}}{6/\sqrt{5}} = \frac{2\sqrt{14}}{6} = \frac{\sqrt{14}}{3}$

Step 4: Determining Coordinates and Latus Rectum

  • Vertices: Since the transverse axis is vertical, vertices are at $(0, \pm a)$.
    Vertices: $(0, \pm \frac{6}{\sqrt{5}})$ or $(0, \pm \frac{6\sqrt{5}}{5})$.
  • Foci: Foci are located at $(0, \pm c)$.
    Foci: $(0, \pm \frac{2\sqrt{14}}{\sqrt{5}})$ or $(0, \pm \frac{2\sqrt{70}}{5})$.
  • Length of Latus Rectum: The formula is $\frac{2b^2}{a}$.
    Length $= \frac{2(4)}{6/\sqrt{5}} = \frac{8\sqrt{5}}{6} = \frac{4\sqrt{5}}{3}$.

Step 5: Visual Representation

V1 V2

Final Solution: Vertices: $(0, \pm \frac{6\sqrt{5}}{5})$; Foci: $(0, \pm \frac{2\sqrt{70}}{5})$; Eccentricity: $\frac{\sqrt{14}}{3}$; Length of Latus Rectum: $\frac{4\sqrt{5}}{3}$

16.
Option B

Solution:

Step 1: Analyzing the Geometric Parameters

Given the ends of the major axis at $(0, \pm\sqrt{5})$ and the ends of the minor axis at $(\pm 1, 0)$, we observe the following:

  • Since the major axis lies on the $y$-axis (the $x$-coordinates of the major axis endpoints are zero), the ellipse is a vertical ellipse [Per the standard form of an ellipse centered at the origin].
  • The standard equation for a vertical ellipse centered at the origin is: $\frac{x^2}{b^2} + \frac{y^2}{a^2} = 1$, where $a > b$.

Step 2: Identifying the Semi-Axes Lengths

The distance from the center $(0,0)$ to the vertex $(0, \pm a)$ provides the semi-major axis $a$.

  • The major axis endpoints are $(0, \pm\sqrt{5})$, thus $a = \sqrt{5}$. Therefore, $a^2 = (\sqrt{5})^2 = 5$.
  • The minor axis endpoints are $(\pm 1, 0)$, thus the semi-minor axis $b = 1$. Therefore, $b^2 = (1)^2 = 1$.

Step 3: Constructing the Ellipse Equation

Substituting the values of $a^2$ and $b^2$ into the standard equation:

$\frac{x^2}{1} + \frac{y^2}{5} = 1$

Step 4: Geometric Visualization

V1(0, √5) V2(0, -√5) B1(1, 0) B2(-1, 0)

Analytical Summary

Parameter Value
Major Axis Orientation Vertical ($y$-axis)
$a^2$ 5
$b^2$ 1

Final Solution: The equation of the ellipse is $x^2 + \frac{y^2}{5} = 1$ or $5x^2 + y^2 = 5$.

Solution:

Step 1: Theoretical Foundation of Point-Circle Relationship

To determine the position of a point $P(x_1, y_1)$ relative to a circle defined by the equation $x^2 + y^2 = r^2$, we calculate the power of the point with respect to the circle. Given the standard equation of a circle centered at the origin $(0,0)$ with radius $r$, the condition is defined by the distance $d$ from the origin to the point $P$.

  • If $x_1^2 + y_1^2 < r^2$: The point lies inside the circle.
  • If $x_1^2 + y_1^2 = r^2$: The point lies on the circle.
  • If $x_1^2 + y_1^2 > r^2$: The point lies outside the circle.

Step 2: Substitution of Given Variables

Given the circle equation: $x^2 + y^2 = 25$, where $r^2 = 25$.

Given the point $P(-2.5, 3.5)$, where $x_1 = -2.5$ and $y_1 = 3.5$.

Substitute these values into the expression $S = x_1^2 + y_1^2$:

$S = (-2.5)^2 + (3.5)^2$

Step 3: Algebraic Calculation

Calculating the squares of the coordinates [Per arithmetic square property $(a)^2 = a \cdot a$]:

$(-2.5)^2 = 6.25$

$(3.5)^2 = 12.25$

Summing the squares: $6.25 + 12.25 = 18.5$

Step 4: Comparison with $r^2$

Comparing the calculated value $18.5$ to the constant $r^2 = 25$:

$18.5 < 25$

Since the sum of the squares of the coordinates is strictly less than the square of the radius, the distance from the origin to the point is less than the radius of the circle [Per distance formula $d = \sqrt{x^2 + y^2} < r$].

Visual Representation

P(-2.5, 3.5) x y

Final Solution: Since $(-2.5)^2 + (3.5)^2 = 18.5$, which is less than 25, the point (-2.5, 3.5) lies inside the circle $x^2 + y^2 = 25$.

Solution:

Step 1: Identification of Hyperbola Orientation and Given Parameters

Given the foci at $(0, \pm 13)$, we observe that the foci lie on the $y$-axis. [Per the standard form of a hyperbola with a vertical transverse axis, the equation is $\frac{y^2}{a^2} - \frac{x^2}{b^2} = 1$].

  • Foci coordinates: $(0, \pm c) = (0, \pm 13) \implies c = 13$.
  • Length of the conjugate axis: $2b = 24 \implies b = 12$.

Step 2: Calculating the Semi-Transverse Axis ($a$)

For any hyperbola, the relationship between the semi-axes and the distance to the foci is governed by the equation $c^2 = a^2 + b^2$. [Per the fundamental hyperbola identity].

Substituting the known values:

$13^2 = a^2 + 12^2$

$169 = a^2 + 144$

$a^2 = 169 - 144$

$a^2 = 25$

$a = 5$

Step 3: Constructing the Equation

With $a^2 = 25$ and $b^2 = (12)^2 = 144$, and identifying the vertical orientation (transverse axis on the $y$-axis), we substitute these into the standard form:

$\frac{y^2}{25} - \frac{x^2}{144} = 1$

Step 4: Visual Representation

F(0, 13) F(0, -13) V(0, 5) V(0, -5)

Step 5: Tabular Summary of Properties

Property Value
Orientation Vertical (Along y-axis)
$a$ $5$
$b$ $12$
$c$ $13$

Final Solution: The equation of the hyperbola is $\frac{y^2}{25} - \frac{x^2}{144} = 1$.

20.
Option A

Solution:

First thing first: noone knows what is going to happen after 1 month or 1 day from now. People who say they do are either simply gambling or trying to fool us. So, we can not say that PNB will come out with bad results unless we have some insider information. Second, markets discount all the information immediately. All the negativity about PNB has already been accounted or discounted in the current price. We can not be wiser than the market. 

Regarding the put option: we know the "risk" but we don't know the "reward" (because we dont know the nature of PNB's results). Therefore the risk-reward being favourable is a false statement as well.

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