Question

The locus of point of trisection of the double ordinates of the parabola y² = 4ax is

• A. 9y² = 4ax
• B. 9x² = 4ay
• C. 4y² =9ax
• D. 4x² = 9ay

Answer 1

Answer: (A)

9y² = 4ax

Answer 2

P=(at², 2at), Q = (at², -2at) are the extremities of double ordinate, let (x, y) divides PQ in the ratio 2:1 then x = at²,

y = $\frac{- 2at}{3}$

By eliminating t, we get 9y² = 4ax