Hello! I am working on a math problem and I can't seem to do it at all. Any help would be greatly apprieciated!! Sorry if the picture is big, but I wanted to draw it to give what's on the paper.

A Farmer has 400 feet of fence and wants to construct a triangular pen using his barn as the boundary for one end of the pen (see figure below - note that no fencing is used along the side against the barn). Use the figure below as well as the information given above to anser the questiosn that follow.

a) Find the function hyp(B), the length of the pen's hypotenuse as a function of the length of its base.