MCQ
The equation of directrix and latus rectum of a parabola are 3x - 4y + 27 = 0 and 3x - 4y + 2 = 0. Then the length of latus rectum is:
  • A
    5
  • 10
  • C
    15
  • D
    20

Answer

Correct option: B.
10
  1. 10
Solution:
$\text{d}=\frac{\text{c}_1-\text{c}_2}{\sqrt{\text{a}^2+\text{b}^2}}$
where dd is the distance between lines whose equations are $a x+b y+C_1=0 \& a x+b y+C_2=0$
$\text{d}=\frac{27-2}{\sqrt{4^2+3^2}}$
= 5 d = 5
If the distance between vertex and latus rectum = distance of vertex from directri x = a
= then d = 2a = 5
⇒ Length of latus rectum = 4a = 10

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

If the line $y - \sqrt 3 x + 3 = 0$ cuts the parabola $y^2 = -x -2$ at $A$ and $B, $ then $PA \cdot PB$ is equal to where $P \equiv ( \sqrt 3 , 0)$
Choose the correct answer: Which of the following is the conditional p → q?
A bag contains $5$ distinct Red, $4$ distinct Green and $3$ distinct Black balls. Balls are drawn one by one without replacement,then the probability of getting a particular red ball in fourth draw is-
If the area of the triangle formed by the positive $x-$axis, the normal and the tangent to the circle $(x-2)^{2}+(y-3)^{2}=25$ at the point $(5,7)$ is $A$ then $24 A$ is equal to ...... .
If $2$ and $6$ are the roots of the equation $a x^2+b x+1=0$, then the quadratic equation, whose roots are $\frac{1}{2 a+b}$ and $\frac{1}{6 a+b}$, is :
A box contains coupons labelled $1,2, \ldots, 100$. Five coupons are picked at random one after another without replacement. Let the numbers on the coupons be $x_1, x_2, \ldots, x_5$. What is the probability that $x_1 > x_2 > x_3$ and $x _3 < x _4 < x _5 ?$
Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion (A) If 5th and 8th term of a GP be 48 and 384 respectively, then the common ratio of GP is 2.
Reason (R) If 18, x, 14 are in AP, then x = 16.
The mean and variance of a set of $15$ numbers are $12$ and $14$ respectively. The mean and variance of another set of $15$ numbers are $14$ and $\sigma^2$ respectively. If the variance of all the $30$ numbers in the two sets is $13$,then $\sigma^2$ is equal to $.........$.
$ABC$ is a triangle in which angle $C$ is a right angle. If the coordinates of $A$ and $B$ be $(-3, 4)$ and $(3, -4)$ respectively, then the equation of the circumcircle of triangle $ABC$ is
The value of $\lambda $, for which the line $2x - \frac{8}{3}\lambda y = - 3$ is a normal to the conic ${x^2} + \frac{{{y^2}}}{4} = 1$ is