The integral $\int_{\pi/4}^{3\pi/4} \frac{dx}{1+\cos x}$ is equal to: (1) $-1$ (2) $-2$ (3) $2$ (4) $4$
The integral $\int_{\pi/4}^{3\pi/4} \frac{dx}{1+\cos x}$ is equal to:
(1) $-1$
(2) $-2$
(3) $2$
(4) $4$