Question

ques

Answer 1

what is the question

Answer 2

From Stoke's Theorem we have
\[\iint_\limits S (\vec \nabla \times \vec F). \hat n \space ds=\oint_\limits C \vec F.d \vec r\]
Where S is any surface and C is a closed curve around the surface
I can see how this works out in the case of a 2D surface


But if we consider the surface of a 3D object, we have

Here S is the lateral surface of that figure
What do we take for our C here??