On the unit circle: the end of the terminal side of a 90 degree angle is (1,0) where 1 is the value of sin(90°) and 0 is the value of cos(90°)
On the graph of sine: 90° = [tex]\frac{ \pi }{2}[/tex] radians. if f(x) = sin(x) in radians, f([tex]\frac{ \pi }{2}[/tex]) = 1/2
