Find cos theta if sin theta=3/4 and theta lies in quadrant 2

By the Pythagorean theorem, the missing side is - sqrt7. The definition of sin is side opposite over hypotenuse, so go into Q2 and make an angle and label the side opposite the angle with a 3 and the hypotenuse a 4. The other leg is - sqrt7 cuz x is negative in Q2. The cosine of an angle is the side adjacent over the hypotenuse, so the cos then is - sqrt7/4