Thread: Normal on a curve

I would be gratefull if anybody can help me on this problem.

Plot the curve y = 1/2X ^ 2 and decide the equation for the
normal lines which can be drawn to the curve from the point (0,9).

Consider a line from to a point on the curve .
Find the slope.of the tangent line to the curve at .
Check when is perpendicular to using slope.