Question

The lats rectum of a parabola whose directrix is x + y - 2 = 0 and focus is (3,-4), is

• A. - $3\sqrt{2}$
• B. $3\sqrt{2}$
• C. $\frac{-3}{\sqrt{2}}$
• D. $\frac{3}{\sqrt{2}}$

Answer 1

The correct option is B

$3\sqrt{2}$

Distance between focus and directrix is

= $\left|\frac{3-4-2}{\sqrt{2}}\right|=\frac{\pm 3}{\sqrt{2}}$

Hence latus rectum = $3\sqrt{2}$

( Since latus rectum is two times the distance between focus and directrix ) .