Question

Решите, будьте добры

Answer 1

$\displaystyle \int\limits^{\frac{\pi}{4}}_0 {\cos2x} \, dx =\frac{\sin 2x}{2} \bigg|^{\frac{\pi}{4}}_0=\frac{\sin\frac{\pi}{2}-\sin 0}{2} =\frac{1}{2}$