$\int_{0}^{\frac{\pi}{2}} \cos ^{3} x \sqrt{\sin x} d x$

$\int_{0}^{\frac{\pi}{4}} \frac{\cos \theta}{\cos ^{2} \theta} d \theta=?$

The value of $\displaystyle\int^{199\pi/2}_{-\pi/2}\sqrt{(1+\cos 2x)}dx$ is?

$\int_0^{\frac{\pi}{4}} \frac{cos 2 \theta}{cos² \theta} = ?$

$\int_{0}^{\pi / 2} \cos x d x=\text { কত? }$