Geometry Angles Cheat Sheet

Understand and identify different types of angles formed by intersecting lines, including their properties and relationships.

Core Principles

• Angles are formed by two rays sharing a common endpoint (vertex).
• Angles are measured in degrees.
• A straight line forms an angle of 180 degrees.
• A right angle forms exactly 90 degrees.
• Understanding angle relationships helps solve geometric problems.

Key Terms

• Adjacent Angles: Angles that share a common vertex and a common side, but do not overlap.
• Vertical Angles: Pairs of opposite angles formed by two intersecting lines. They are always equal.
• Complementary Angles: Two angles whose measures add up to 90 degrees.
• Supplementary Angles: Two angles whose measures add up to 180 degrees.
• Linear Pair: Two adjacent angles that form a straight line (180 degrees).
• Right Angle: An angle that measures exactly 90 degrees.
• Straight Angle: An angle that measures exactly 180 degrees.

Real World Examples

• Clock hands at 3:00: Forms a right angle (90 degrees).
• A straight road: Represents a straight angle (180 degrees).
• Scissors blades crossing: Forms vertical angles.
• Corner of a book: Forms a right angle (90 degrees).
• Two roads intersecting: Creates vertical and supplementary angles.

Quiz

• If angle A is 40 degrees, what is its complementary angle?: 50 degrees
• Two intersecting lines form angles. If one angle is 110 degrees, what is its vertical angle?: 110 degrees
• Angles that share a vertex and a side are called:: Adjacent angles