> restart:

> a:=3:b:=4:c:=sqrt(a^2+b^2):

> x0:=c*cos(t):

> y0:=a+c*sin(t):

> z0:=0:

> s:=arccos(b/c):

> x1:=x0*cos(s)-z0*sin(s):

> y1:=y0:

> z1:=x0*sin(s)+z0*cos(s):

> x:=x1*cos(u)-y1*sin(u):

> y:=x1*sin(u)+y1*cos(u):

> z:=z1:

> plot3d([x,y,z],t=0..2*Pi,u=0..Pi,scaling=constrained,grid=[20,20],
lightmodel=light3,title="87121 By J.S.C.");