As part of my homework I've the following problem:
Find the shortest path from corner $S$ to corner $F$ (the spider should walk on the surface).
I have to use calculus to solve the problem (more specifically using the absolute min/max theorems).
I'm struggling to come up with a "primary function" to derive and apply the absolute max/min theorems.
My guess is that i have to find the shortest path from corner $S$ to the end of the common edge (between the planes) and add to that the shortest path from that edge the corner $F$, but i'm unable to construct appropriate function (should i use the distance formula?).