5-1	Construct the envelope of the light rays emitted from a radiant point source at infinity after reflection by the semi-circle.
5-2	radiant point source at the circumference after reflection by the same circle.
5-3	Construct the envelope formed by a fix diameter of a circle rolling along a straight line.
5-4	Construct the envelope formed by a fix diameter of a circle rolling along a fixed circle of the same size.
5-5	Construct the envelope formed by a fix diameter of a circle rolling along a fixed circle twice the diameter.
5-6	Construct this figure:
5-7	Construct this figure:
5-8	Construct this design:
5-9	Construct the nested squares as thus:
5-10	Constructed nested triangles as thus:
5-11	Construct this pattern:
5-12	Construct the family of ellipses  as t ranges in [0,1].
5-13	Construct the concentric and coaxial ellipses of constant area:
5-14	Construct this pattern.
5-15	Construct this pattern.
5-16	Construct the reflections of a light ray trapped inside a reflective ellipse. There are two cases.