Consider the curve y = cosh x for x between -a and a. 
Remember that cosh x = (exp(x) + exp(-x))/2; see reading hwk
assigned on Oct 14. 

(1) Now this curve rotates about the y-axis, and you obtain a 
tulip shaped surface. Calculate its area.


(2) Now let the same curve rotate about the x-axis. You get
a surface that looks a bit like a yoyo, or maybe a bike wheel with the
rubber missing (and minus the spikes holding the wheel in place)
Calculate the area of that surface.