1. The problem statement, all variables and given/known data Evaluate cos(θ + π/2) if sin θ = 3/7, exactly. 2. Relevant equations How do I go about doing this exactly instead of approximately on the calculator? 3. The attempt at a solution The only way I know how to do it is taking the inverse sin of 3/7 and adding 90 degrees and taking the cos of that result. Thank you for your time!