在这点上，我们有一个切于等值面的切面，这就是等值面的切平面。

And, at this point, I have the tangent plane to the level surface OK, so this is tangent plane to the level.

youdao

在这点上，我们有一个切于等值面的切面，这就是等值面的切平面。

And, at this point, I have the tangent plane to the level surface OK, so this is tangent plane to the level.

youdao