Question

The locus of the point of intersection of tangents drawn at the extremities of a normal chord to the parabola `y^2=4ax` is the curve
A. x=a
B. x=-a
C. y=a
D. y=-a

Answer 1

Correct Answer - B
From illustration 4, we have
`m_(1)m_(2)=a/h`
If the tangents are perpndicular, then
`m_(1)m_(2)=-1rArra/h=-1rArrh=-a`
Hence, the locus of (h, k) is x=-a, which is the directrix of the parabla.