Well, for example,if our surface is a plane, a slanted plane given by some equation, ax by cz = d.

比如说，假如我们的曲面是一个平面，由公式ax+by+cz=d给出的，一个倾斜的平面。

youdao

z Maybe we don't know how to solve for z as a function of x and y, but our surface is given by some equation.

也许我们不知道如何直接用x，y表示，但是曲面是由某些方程给出的。

youdao

I have a parametric equation for my surface.

有曲面的参数方程。

youdao