Plot of the cone "conez1"

> implicitplot3d(conez1,x=-1..1,y=-2..2,z=-3..3,scaling=constrained,axes=frame,grid=[15,15,15]);

Here, a "grid=[15,15,15]" option was needed in order to make the cone join-up at the centre. The default grid is too coarse for Maple to plot this properly.

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