See section 11.10.3 for general polygons in the plane.

The polygon command takes as arguments a sequence of points.

polygon returns and draws the polygon whose vertices are the given points.

Input:

A := point(0,0,0); B := point(3,3,3);

C := point(0,0,3); D := point(-3,-3,0);

E := point(-3,-3,-3)

C := point(0,0,3); D := point(-3,-3,0);

E := point(-3,-3,-3)

then:

polygon(A,B,C,D,E)

Output: