Let C be the semi circle on the surface from to which passes through the point ( , , ) (note that x=y for all (x,y,z) on C.)

Evaluate the integral

(Suggestion: use as your parameter the angle Q subtended at the orgin by the arc NP for a point P on C)

I think i need to sketch the picture to understand it, but Im having a hard time to do it, is there another way to find x,y,z in term of t?