What is the value of [math]\displaystyle\int_{0}^{\infty} \dfrac{x}{x^2+a^2}\,dx [/math]?
What is the value of [math]\displaystyle\int_{-1}^1 \frac{\sqrt{1-x^2}}{a-x} \, dx[/math] where [math]a > 1[/math]?