Question

1: Length of lactus rectim of parabola with vertex(1,2) and directrix 3x-4y-2=0 is
A) 27/5 B) 18/7 C) 28/5
i kniw the formula to find length of lactus rectum =4a

Answer 1

The distance from (1,2) to the line 3x-4y-2=0 is

|3*1-4*2-2|/√(3^2+4^2) = 7/5

If the parabola is expressed in the form

y^2 = 4ax,

then the distance from the directrix to the vertex is a.

So, 4a = 28/5

Answer 2

Thank u soo mch fr helpin me out..