So how do I show that ?
The only solution I've found is to write it as and then make a crazy change of variables that rotates the coordinate system by . But that gets really messy.
Hmmm...I believe you would have to use a power series representation here.
If we take the integral of this,
Note how this is the series,
Edit- Can you explain your way? I don't quite comprehend what you were trying to do but it seems like a cool exercise (so if you could, could you post your solution?)