Cosine of Angle plus Right Angle

Theorem

 * $\map \cos {x + \dfrac \pi 2} = -\sin x$

Also see

 * Sine of Angle plus Right Angle
 * Tangent of Angle plus Right Angle
 * Cotangent of Angle plus Right Angle
 * Secant of Angle plus Right Angle
 * Cosecant of Angle plus Right Angle