Draw the perspective view of a tetrahedron of 30 mm edge when resting on ground plane on one of its faces with one of resting edges parallel to the picture plane. The vertical axis of the tetrahedron is in between this parallel edge and the picture plane, and 30 mm behind it. The station point is 45 mm in front of the picture plane, 50 mm to the left of the axis and 40 mm above the ground.