This should be relitively simple: y = x ... convert to spherical coords: p*sin(r)*sin(t) = p*sin(r)*cos(t) which reduces to... sin(t) = cos(t) tan(t) = 1 (is this right?) t =~ 0.78... (Can i get a nice fraction for this?) Any help is appreciated. - glog
in other words, "y= x" in spherical coordinates reduces to the set of points where t= [itex]\theta= \pi/4[/itex], r= [itex]\phi[/itex] and p= [itex]\rho[/itex] can be anything. Do you see that that is, in fact, the same as the plane y= x?