A tangent to the parabola x2=4ay meets the hyperbola x2−y2=a2 at two points P and Q, then midpoint of P and Q lies on the curve
y3=x2(y−a)
Equation of tangent to parabola y=mx−am2......(1)
equation of chord of hyperbola whose midpoint is (h, k) is
hx−ky=h2−k2...... (2)
form (1) and (2)
mh=1k=am2h2−k2⇒k3=h2(k−a)