Cosine is the x-value divided by the hypotenuse. We now know that since cosine is 3/8, that the hypotenuse is 8. In order to find the third side of the triangle (which would be the v-value), we must use Pythagorean theorem. The third side is square root 55. Sine equals the y-value divides by the hypotenuse. We know both of those values, so Sine of theta = square root of 55 divided by 8.
