# Math Help - proof

1. ## proof

Hi, my teacher gave me this proof to do for homework but I can't figure out where to even start. He wants us to prove that ∫du/(a^2+u^2 ) = 1/a arctan〖u/a〗+C, and also the same thing for the similar arcsin identity. He also said to use differentiation to prove this. Not really sure what to do.

2. Differentiate $\frac{1}{a}\arctan\frac{u}{a} +C$ and verify that it is equal to $\frac{1}{a^2+u^2}$.

Hint: $\frac{d}{du}\left( \arctan u \right)=\frac{1}{1+u^2}$

3. thanks.