# How do you prove sin(pi/4 + x) = cos (pi/4 - x)?

Expand the terms and use the identity ${\sin}^{2} \left(x\right) + {\cos}^{2} \left(x\right) = 1$
${\sin}^{2} \left(x\right) + {\cos}^{2} \left(x\right) = 1$