Question

If the parabola $x^2=4ay$ passes through the point $(2, 1)$, then the length of the latus rectum is

• A. 1
• B. 4
• C. 2
• D. 8

Answer 1

Answer: (B)

$x^{2}=4 a y$
Given parabola passes through $(2,1)$.
$\Rightarrow 2^{2}=4 a$
$\Rightarrow a=1$
Length of latus rectum= $4 a=4$.