Question

Calculus question?

Answer 1

A man owns a rectangular plot of land size 120 x 200 feet. Pipe is to be laid from A to point P on side BC and from there to C. The cost of laying pipe through the lot is $30 per foot and the cost along the side of the plot is $25 per foot. How many feet should be along the side of the lot for the least expensive layout of the pipe?

Answer 2

Then it gives me a picture that looks like that. I usually like optimization problems, but this one is tripping me up. What exactly am I optimizing? It already says pipe needs to be layed from A to P and from P to C...