# Unit normal vector to the curve of a function at a point

How can I derive the formula for the normal unit-vector to the curve of a function at a given point $p$?

-

## 1 Answer

If curve is represented by $f(x,y)=0$, then $\nabla f_{(x_0,y_0)}$ is normal vector to curve at point $(x_0,y_0)$

-
What's the name for that reflected $\Delta$? –  saadtaame Mar 7 '13 at 19:29
'nabla', it is. –  Aang Mar 7 '13 at 19:34