Maths-
General
Easy

Question

The locus of the poles of focal chord of the parabola y2 = 4ax is

  1. x + 2a = 0    
  2. its directrix    
  3. x + 4a = 0    
  4. 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 rightwards double arrow a + h = 0 rightwards double arrow a + x = 0

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