##### Geometry Basic Vocabulary (Angles)

**Angle**

The intersection of two non collinear rays at a common endpoint. The rays are called sides and the common end point is called the vertex.

**Vertex**

the common endpoint

**Angle bisector**

A ray that divides and angle into the congruent angles.

**Complementary angles**

Two angles with measures that have a sum of 90.

**Supplementary angles**

Two angles with measures that have a sum of 180.

**Vertical angles**

two nonadjacent angles formed by two intersecting lines.

L 1 and L 3 are vertical angles

L 2 and L 4 are vertical angles

**Adjacent angles**

Two angles that lie in the same plane have a common vertex and a common side, but no common interior points.

**Linear pair**

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

**Degree**

A unit of measure used in measuring angles and arcs. An arc of a circle with a measure of 1* is 1/360 of the entire circle.

**Acute angle**

an angle with a degree measure less than 90.

**Obtuse angle**

an angle with degree measure greater than 90 and less than 180.

**Right angle**

An angle with a degree measure of 90.