See section 13.8.4 for parallelograms in space.
The parallelogram command takes three mandatory arguments and one optional argument. The mandatory arguments are three points A, B and C.
parallelogram returns and draws the parallelogram
ABCD for the appropriate D.
Input:
Output:
The fourth optional argument will need to be
a variable name which will be assigned to vertex D.
Input:
Output:
Input:
Output: