$$\int_\limits0^{\frac{\pi}{4}} \log \left(\frac{\sin x+\cos x}{\cos x}\right) d x=$$

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

$\int_\limits{\frac{-\pi}{4}}^{\frac{\pi}{4}}(\sin x)^{-4} \mathrm{~d} x$ has the value

$\int_\limits0^{\frac{\pi}{2}}|\sin x-\cos x| d x$ has the value