Answer: 22.5
Explanation: from P the radii of length r are perpendicular to xz, xy, and yz and all the same.
if draw it with your compass your see a certain symmetry
call the tangent point on xz Q and the one on xy S
triangle XQP is congruent to XSP and is a right triangle
the two angles at x are 22.5 degrees
so PQ = PS = 4 tan 22.5
