Sine and cosine

Sine and cosine are trigonometric functions. They both can be graphed. When trying to find an angle of a right right triangle, you would use sine by saying sin(angle)=opposite/hypotenuse. If you were to use cosine, you would say cos(angle)=adjacent/hypotenuse. Both sine and cosine's graphs are very similar, except that sine starts at x=0 while cosine starts at the high test point of the graph's period. There are various trig identifies concerning sine and cosine, including sum/difference, half angle, and double angle identities.