trig
posted by billy .
give the exact real number value without using a calculator
sin[(cos^1)(1/4)]
sin[(tan^1)(3/4)+(tan^1)(12/5)]

On each of these, draw the triangle. On the first, the adjacent side is 1, the hyp is 4, so the opposite side is sqrt(161) So sine of that angle is sqrt15/4
Same idea on the next.