I have a big project- worth half a test- and I need some help. I don't want anyone to do the work for me- just help me get unstuck, and point to what I should be looking for.

The project gives a few illustrtions, and then asks some questions. The actual assignment can be found at http://books.google.com/books?id=_cIT_pRdfJIC&pg=PA573&lpg=PA573&dq=Fresnel+lens+trig+cohen&source=bl&ots=HjLGbQWcT9&sig=aPNKGMwAoAsfyvsEX3aCJCW5joE&hl=en&ei=MDgmTrnzO6nmiALe04j0CQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBkQ6AEwAA#v=onepage&q&f=false.

On Exercise 1, part B, I get the first part- its from basic geometry that these angles are equal. But the next ones, asking to verify that 02 = B + A2, and so on, I just don't know where to start.

Should I be looking for geometry, or rotating around a unit circle to understand these? Or is this a matter of using some identities?

Sorry I can't ask a better question- I'm just stumped at this point.

I'm sure I"ll have more questions. I'm having trouble knowing how to apply the trig I DO know to this problem.

Thanks for your help!

Wayne