
7.10 Differential geometry
Problem:
Find the equations of the tangent plane of the torus.
\[
\begin{array}{l}
x=(7+5 \cos u) \cos v, \quad y=(7+5 \cos u) \sin v, \\
z=5 \sin u, \quad \text { at the point } M(u, v) .
\end{array}
\]