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Angles

# Angles

An angle is formed when lines or line segments meet.

Lesson Demo

An angle is formed when lines or line segments meet.

The lines that form an angle are called the sides or the arms of the angle.

The common end point is called the vertex of the angle.

The angle formed by two lines or line segments can be an acute angle, where the measure of the angle is less than 900.

The angle formed by two lines or line segments can be a right angle, where the measure of the angle is900.

The angle formed by two lines or line segments can be an obtuse angle, where the measure of the angle is greater than 900.

The angle formed by two lines or line segments can be a straight angle, where the measure of the angle is equal to 1800.

The angle formed by two lines or line segments can be a reflex angle, where the measure of the angle is greater than 1800.

When the sum of the measures of two angles is 900, the angles are called complementary angles.

When the sum of the measures of two angles is 1800, the angles are called supplementary angles.

Adjacent angles have a common vertex and a common arm, and the non–common arms are on either side of the common arm.

A linear pair is pair of adjacent angles whose non–common sides are opposite rays.

Vertically opposite angles are opposite to each other and are equal.

Adjacent angles have no common interior points.

The angles in a linear pair are supplementary.