Properties of Rectangles
ABCD is a rectangle with diagonals AC and BD that meet at point O.
A rectangle is a parallelogram with four right angles. Angles A, B, C, and D are all right angles.
The opposites sides of a rectangle are parallel and congruent. This means 
and
.
The properties of parallelograms also hold true for rectangles. Opposite angles are congruent, consecutive angles are supplementary, and the diagonals bisect each other.
There is one additional property of the diagonals of a rectangle. If a parallelogram is a rectangle, then its diagonals are congruent. This means
.