What are sines?

Answer by  PaulM (21)

The sine is a function of angle. Imagine a circle of radius r centered at the origin of an x-y plane. Starting with a pencil at the circle's rightmost point (r,0), trace counterclockwise along the circle. At any point, let the angle that has been swept with respect to the origin be called a. The sine of a is y/r.

Answer by  VB (361)

The sine of an angle is the ratio of two sides of a right triangle. The short hand for the formula is sin A = opposite/hypotenuse. The hypotenuse is always the longest side of the right triangle opposite the right angle and the opposite side is the side of the triangle that doesn't touch angle A.