12-9

> restart;

> z:=rho*cos(phi);

> r:=rho*sin(phi);

> x:=r*cos(theta);

> y:=r*sin(theta);

> simplify((x^2+y^2+z^2)^2=2*z*(x^2+y^2));

> rho:=2*cos(phi)*sin(phi);

> p1:=plot3d([x,y,z],theta=0..Pi,phi=0..Pi/2,grid=[50,50]):

> p1;

> p2:=plot3d([x,y,z],theta=0..Pi,phi=0..Pi,grid=[50,50]):

> p2;

> with(plottools):

> vrml(p2,"c:/program files/maple 6/beauty/12-9.wrl",background_color=white);

>