Beginning of Geometry

An angle that measures less than 90 degrees.

• Acute Angle

• Straight Angle

• Right Angle

• Obtuse Angle

Part of a line consisting of two endpoints and all points in between them.

• Ray

• Line

• Line Segment

• Straight Angle

A flat surface with no thickness that extends in all directions forever.

• Ray

• Line

• Plane

• Parallelogram

A location that has no size.

• Ray

• Point

• Plane

• Dot

Two or more lines that share a common point of intersection.

• Parallel Lines

• Intersecting Lines

• Ray

• Line Segment

Two lines in the same plane that will never intersect

• Parallel Lines

• Skew Lines

• Perpendicular Lines

• Line Segment

A triangle with two congruent sides

• Equilateral Triangle

• Isosceles Triangle

• Scalene Triangle

• Right Triangle

A triangle with no congruent sides

• Equilateral Triangle

• Isosceles Triangle

• Scalene Triangle

• Right Triangle

Two angles that sum to 180 degrees.

• Complimentary Angles

• Supplementary Angles

• Right Angles

• Obtuse Angles

Two angles that sum to 90 degrees.

• Complimentary Angles

• Supplementary Angles

• Right Angle

• Obtuse Angle