This document defines and provides constructions for three special parallelograms: rhombi, rectangles, and squares. It states that a rhombus is an equilateral parallelogram, a rectangle is an equiangular parallelogram, and a square is an equilateral equiangular parallelogram. Constructions using a straightedge are provided for each. Properties of the diagonals are given for each shape: the diagonals of a rhombus are perpendicular and bisect each other and the angles, the diagonals of a rectangle are congruent and bisect each other, and the diagonals of a square are congruent, perpendicular, and bisect each other.
