9. Equation of tangent in different forms

Parabola equation y² = 4ax; at point (x1,y1)
(y-y1) = (2a/y1)*(x-x1)
=> yy1 = 2a(x+x1)

In parametric form Points is (at²,2at)
ty = x+at²

In terms of slope of the tangent, If slope is m
y = mx + a/m