Here are the commands that you can give to Maple to draw a square-based pyramid. You need to know the coordinates of the vertices, and for each face, you need to know the order in which the vertices appear around the face. The first command loads some graphics macros. The next five lines give the coordinates of the five vertices. The next five lines list which vertices are on each face. The next line defines the polyhedron as the collection of faces. The last line displays it. You don't have to use the symbols ; you can chooses other names for the vertices, faces, and polyhedron.
with(plots); v1:=[1,1,0]; v2:=[-1,1,0]; v3:=[-1,-1,0]; v4:=[1,-1,0]; v5:=[0,0,1]; f1:=[v1,v2,v3,v4]; f2:=[v1,v2,v5]; f3:=[v2,v3,v5]; f4:=[v3,v4,v5]; f5:=[v4,v1,v5]; p:=[f1,f2,f3,f4,f5]; polygonplot3d(p,scaling=constrained);