Reciprocal of One Plus Sine

Theorem

 * $\dfrac 1 {1 + \sin x} = \dfrac 1 2 \map {\sec^2} {\dfrac \pi 4 - \dfrac x 2}$

Also see

 * Reciprocal of One Minus Sine


 * Reciprocal of One Plus Cosine
 * Reciprocal of One Minus Cosine