X^2 = 4ay
X^2 = 4y therefore a = 1
Let P(2ap,ap^2) = P(2p,p^2) and Q(2q,q^2) (p>0, q<0)
Show eqn of tangent at P is y = px – p^2
Show eqn of tangent at Q is y = qx – q^2
Solve simultaneously to show T(p+q , pq)
Show eqn of normal of normal at P is y – p^2 = -(1/p)(x – 2p)...