# Angles of an Isosceles Trapezoid

How to solve the angles of an isosceles trapezoid problems: properties, example, and its solution.

## Definition

An isosceles trapezoid is a trapezoid

whose legs are congruent.

Its base angles (blue angles) are also congruent,

just like an isosceles triangle.

## Properties

There are two properties

related to the angles of an isosceles trapezoid.

The base angles are congruent.

(= Same colored angles are congruent.)

An isosceles trapezoid is also a trapezoid.

So the sum of the measures

of the consecutive interior angles is 180.

(purple & blue angles)

Angles of a trapezoid

## Example

∠*D* and ∠*C* are the base angles,

which are congruent.

So m∠*D* = m∠*C* = 60.

∠*A* and ∠*D* are the consecutive interior angles.

So m∠*A* + m∠*D* = 180.

m∠*A* + 60 = 180.

∠*A* and ∠*B* are the base angles,

which are congruent.

So m∠*A* = m∠*B* = 120.