Well, no one answered. It's a simple enough problem to do by integration by parts but I like the solution I found as it doesn't have to do with parts.

Let giving dx = - dz.

Then

After some work with the addition of angles formulas:

x and z are "dummy" variables so change the z on the RHS to x and move the last term on the right to the LHS:

The integral on the RHS is elementary and gives:

-Dan