# Math Help - Normal on a curve

1. ## 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).

2. Consider a line $l$ from $(0,9)$ to a point on the curve $(a, \frac{1}{2}a^2)$.
Find the slope.of the tangent line $l'$ to the curve at $x=a$.
Check when $l$ is perpendicular to $l'$ using slope.