Key Terms Understanding Geometry

Part of a line that consists of two points, called endpoints.

• Line
• Ray
• Angle
• Line segment

A point that divides, or bisects, a segment into two congruent segments

• Midpont
• Vertex
• Bisector
• Intersection

An angle with measure between 90° and 180

• Acute angle
• Obtuse angle
• Right angle
• Straight angle

Two dimensional and extends without end, even though the drawing appears to have edges

• Line
• Line segment
• Plane
• Ray

Has no dimension and is represented by a dot 

• Point
• Plane
• Line
• Line segment

Part of a line that consists of a point called an endpoint and all points on the line that extend in one direction

• Plane
• Line segment
• Ray
• Angle

An angle with measure equal to 90°

• Acute angle
• Complementary angle
• Straight angle
• Right angle

An angle with measure equal to 180°

• Straight angle
• Supplementary angle
• Linear pair
• Obtuse angle

Two angles whose measures have the sum 180°

• Complentary angles
• Supplementary angles
• Obtuse angle
• Straight angle

Two angles whose sides form two pairs of opposite rays

• Vertical angles
• Adjacent angles
• Straight angle
• Linear Pair