How do I solve this problem?

Question

The sin A = 0.5. Find the angle A = ?. Using this relationship of sine and cosine being complements, what is the angle that would have the same cosine value as the sine of A?

Answer 1

Generally, there are certain values of sin and cos that would be good to just memorize in order to have at your disposal quickly. One of them happens to be sin 30^o = 0.5. Unfortunately, there isn't some trick to getting this value, it's just a good one to know. However, once you know the angle, the second question is easier to answer, since the complement on an angle is that angle subtracted from 90, so 90 - 30 = 60, so cos 60 = sin 30.

Answer 2

If sin A = .5, then A = 30° and cos 60° is 1/2.