if x=3sinAcosB,y=3sinAsinB and Z=3cosA then find the value of xsqr+ysqr+zsqr

Hi Mazz, given x = 3 sin A cos B ==> x^2 = 9 sin^2 A cos^2 B
And y = 3 sin A sin B ===> y^2 = 9 sin^2 A sin^2 B
So x^2 + y^2 = 9 sin^2 A ( cos^2 B + sin^2 B) = 9 sin^2 A
Also z = 3 cos A ===> z^2 = 9 cos^2 A
So x^2 + y^2 + z^2 = 9 sin^2 A + 9 cos^2 A = 9 (sin^2 A + cos^2 A) = 9