consider a symmetric cross inscribed in a circle of radius r

http://img593.imageshack.us/img593/5237/cross.png

a) Write the area A of the cross as a function of x and find the value of x that maximizes the area.

b) Write the area A of the cross as a function of θʹ and find the value of θʹ that maximizes the area.

c) Show that the critical numbers of parts (a) and (b) yield the same maximum area. What is the area?