Smooth Local Parametrization of Surface of Revolution

Theorem
Let $S_C$ and $C$ be the surface of revolution and its generating curve.

Let the smooth local parametrization of $C$ be:


 * $\map \gamma t = \tuple {\map x t, \map y t}$

Then the smooth local parametrization of $S_C$ can be written as:


 * $\map X {t, \theta} = \tuple {\map y t \cos \theta, \map y t \sin \theta, \map x t}$

where $\tuple {t, \theta}$ belongs to a sufficiently small open set in the plane.