Question

The length of latus rectum of he parabola, whose focus is (a sin2θ, a cos2θ) and directrix is the line y = a, is

(a)  |ra cos²θ|

(b)  |4a sin²θ| 

(c)  |4a cos²θ|

(d)  |a cos²θ|

Answer 1

Correct option (b)  |4a sin²θ| 

Explanation:

Distance of focus from directrix is |a cos 2θ – a|. Thus length of latus rectum is |4a sin²θ|