Geometry Vocabulary: Unit Two

Point

Something that marks a specific location or position

Line

A straight path that has no thickness and extends in both directions. Doesn’t bend.

Line segment

A straight path that connects two specific endpoints and has a measurable length

Colinear

Points that lie on the same line

Plane

A flat surface that extends without end

Ray

A subset of a line that extends to infinity in one direction from one endpoint.

Acute angle

An angle measure between 0 and 90.

Obtuse angle

An angle measure greater than 90 but less than 180

Straight angle

An angle that is exactly 180.

Right angle

An angle that is exactly 90

Reflex angle

An angle that is greater than 180 but less than 360

Adjacent angles

Two angles that have a common vertex and a common side. They are touching each other.

Vertical angles

Pairs of adjacent angles formed by two intersecting lines.

Complementary angles

Two angles whose measures have a sum of 90. Each angle is called the - of each other.

Linear pair

A pair of adjacent supplementary angles

Supplementary angles

Two angles whose measures have a sum of 180. Each angle is called the - of each other.

Angle bisector

A line, line segment, or a ray that divides an angle into two congruent angles.