Question:
The length of the latus rectum of a parabola, whose vertex and focus are on the positive $x$-axis at a distance $R$ and $S(>R)$ respectively from the origin, is :
Correct Option: , 3
Solution:
$\mathrm{V} \rightarrow$ Vertex
$\mathrm{F} \rightarrow$ focus
$\mathrm{VF}=\mathrm{S}-\mathrm{R}$
So latus rectum $=4(\mathrm{~S}-\mathrm{R})$