Problem 1716 (difficulty: 6/10)

a) \(\displaystyle \displaystyle \int\limits_0^\infty \frac{\cos ax}{x^2+a^2}\dx\)    \(\displaystyle (a>0)\)    b) \(\displaystyle \displaystyle \int\limits_0^\infty \frac{x\sin x}{x^2+a^2}\dx\)

Give me another random problem!