Primitive of Arccotangent of x over a/Proof 1

Theorem

 * $\displaystyle \int \operatorname{arccot} \frac x a \ \mathrm d x = x \operatorname{arccot} \frac x a + \frac a 2 \ln \left({x^2 + a^2}\right) + C$

Proof
Let:

Then: