Show that in the parabola y^2 = 4ax, the radius of curvature at any point P is twice the part of the normal intercepted between the curve and the directrix.

Show that in the parabola y^2 = 4ax, the radius of curvature at any point P is twice the part of the normal intercepted between the curve and the directrix. Show that in the parah'la y 2 the radius of curvature at any point P is twice the part of the normal intercepted between the curve and the direclrix.