Question

The value of integral ${\int }_{{\pi }_{/4}}^{\pi /2}\cos xdx$ is?

Answer 1

${\int }_{{\pi }_{/4}}^{\pi /2}\cos xdx{\sin x|}_{\pi /4}^{\pi /42}\sin \frac{\pi }{2}-\sin \frac{\pi }{4}1-\frac{1}{\sqrt{2}}=\frac{\sqrt{2}-1}{\sqrt{2}}$