Putting the two cylinders and the space curve on the same plot

> p1:=implicitplot3d('x'^2+'y'^2=1,'x'=-1..1,'y'=-1..1,'z'=-0.5..2):

> p2:=plot3d('x'^2,'x'=-1.5..1.5,'y'=-1.5..1.5):

> p3:=spacecurve([x,y,z],t=0..2*Pi,color=red,thickness=3):

> display({p1,p2,p3},scaling=constrained,axes=frame,labels=['x','y','z']);

Beautiful!

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