Maths-
General
Easy
Question
The locus of the poles of focal chord of the parabola y2 = 4ax is
- x + 2a = 0
- its directrix
- x + 4a = 0
- None of these
The correct answer is: its directrix
If (h, k) be the pole, then equation of chord
ky = 2a (x + h), it passes through focus (a, 0)
so 2a (a + h) = 0 
a + h = 0 a + x = 0
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