Sine of Right Angle

Theorem

 * $\sin 90 \degrees = \sin \dfrac \pi 2 = 1$

where $\sin$ denotes the sine function.

Proof
A direct implementation of Sine of Half-Integer Multiple of Pi:
 * $\forall n \in \Z: \map \sin {n + \dfrac 1 2} \pi = \paren {-1}^n$

In this case, $n = 0$ and so:
 * $\sin \dfrac 1 2 \pi = \paren {-1}^0 = 1$

Also see

 * Cosine of Right Angle
 * Tangent of Right Angle
 * Cotangent of Right Angle
 * Secant of Right Angle
 * Cosecant of Right Angle