Question

I need help on number 59. It makes no sense to me, I cannot figure out how I would use Pythagorean identities to solve this. Please help!

Answer 1

If you have never used a unit circle, I recommend making one. 
R for the following degrees are
30*= 4((3^1/2)/2)^2
60*= 8(2^1/2)(2^1/2)^2
90*= (8((3^1/2)/2))/4