First, you used 2 to multiply by 1:

Then, you used to add 0:

Then, you split and :

And as you can see in the end, all this work was an elaborate plan to achieve a cancellation and split it into two easier integrals:

First integral should be simple enough for you, and as for the second integral, you should see that by taking 2 out as a factor and doing some manipulation, you'll get a standard arctan form.