Rectangles

A rectangle is a parallelogram with four right angles.

Properties (inherits all parallelogram properties, plus)

• All four angles are 90°.
• Diagonals are congruent.
• Diagonals bisect each other (parallelogram property).

Proving a Rectangle

• Show it is a parallelogram with one right Angle (then all are right angles).
• Show it is a parallelogram with congruent diagonals.
• Show all four angles are right angles.

Rectangle vs Parallelogram

Every rectangle is a parallelogram, but not every parallelogram is a rectangle. The special property is the right angles (or equivalently, congruent diagonals).