What is sin pi 2?

Sin pi/2 is equal to 1. It represents the sine of the angle pi/2, which is 90 degrees in radians. The sine function relates the opposite side of a triangle to its hypotenuse, and in a right triangle with one angle equal to pi/2, the opposite side to this angle is the longest side, also called the hypotenuse. Therefore, sin pi/2 is equal to 1, as the hypotenuse is equal to itself.