# Rectangles

A parallelogram in which all the angles are right angles is called a rectangle.

Since a general property of all parallelograms is that all adjacent angles are supplementary (add up to 180°), it is obvious that if a parallelogram has **one** right angle (90°), then **all** the other angles are also 90°

In addition to the general properties of parallelograms, in a rectangle, the diagonals are of equal length,

We will show these properties using triangle congruence.

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*Now that we've explained the basic concept of rectangles in geometry, let's scroll down to work on specific geometry problems relating to this topic.*