Sine of Three Right Angles

Theorem

 * $\sin 270^\circ = \sin \dfrac {3 \pi} 2 = - 1$

where $\sin$ denotes the sine function.

Also see

 * Cosine of Three Right Angles
 * Tangent of Three Right Angles
 * Cotangent of Three Right Angles
 * Secant of Three Right Angles
 * Cosecant of Three Right Angles