You can only find the values of the derivatives at specific points. Differentiate both for r, then both for s, and evaluate at to get:
The values will be given, so the previous four equations form an algebraic system to be solved for .
How do I find the partial derivatives of x(r,s) or y(r,s) implicitly? I tried implicit differentiation and I got 2 different answers for either. Can someone show me any of the 4 derivatives step-by-step?