with(plots):
u:=(x,y)->2*x^2+3*y^2: v:=(x,y)->4-x^2-2*y^2:
a:=2/sqrt(3): b:=2/sqrt(5):
qumian1:=plot3d([a*r*cos(t),b*r*sin(t),u(a*r*cos(t),b*r*sin(t))],t=0..2*Pi,r=0..1,color=blue,style=wireframe):
qumian2:=plot3d([a*r*cos(t),b*r*sin(t),v(a*r*cos(t),b*r*sin(t))],t=0..2*Pi,r=0..1,color=black,style=wireframe):
quxian:=spacecurve([a*cos(t),b*sin(t),u(a*cos(t),b*sin(t))],t=0..2*Pi,color=red,thickness=4):
x_axis:=plot3d([u,0,0],u=-1..1,v=0..0.01,thickness=3):
y_axis:=plot3d([0,u,0],u=-1..1,v=0..0.01,thickness=3):
z_axis:=plot3d([0,0,u],u=-.2..5,v=0..0.01,thickness=3):
xyz:=display(x_axis,y_axis,z_axis,thickness=3):
display(qumian1,qumian2,quxian,xyz,scaling=constrained,orientation=[40,60]);
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