The value of $$\int_{-\pi / 2}^{\pi / 2} \frac{\cos x}{1+e^x} d x$$ is

$$\int_\limits{-3}^3 \cot ^{-1} x d x=$$

$$\int_\limits0^2\left[x^2\right] d x=$$

$$\int_\limits0^1 \sqrt{\frac{1+x}{1-x}} d x=$$