Angles Summary

Geometry · Axiom Academy

SUMMARY Unit 2 Summary: Angles Everything from measuring a single angle to the family of equal and supplementary angles that parallel lines create. An angle is classified by its measure: acute ( ), right ( ), obtuse ( – ), and straight ( ). Complementary angles sum to ; supplementary angles sum to . (Corner = 90, Straight = 180.) When two lines cross, the vertical (opposite) angles are congruent , and each adjacent pair forms a linear pair that is supplementary. A transversal across parallel lines makes corresponding, alternate-interior, and alternate-exterior angles congruent ; co-interior (same-side interior) angles are supplementary . Almost every angle problem reduces to one move: set up an equation from " ", " ", or " ", then solve for the unknown. Core Concept Measuring & Classifying Angles An angle measures the turn between two rays sharing a vertex, in degrees from to . We name an angle by its size: When to use: first step in any problem — name the angle so you know what bounds it. Watch out for: right and straight angles are exact values, not ranges. Core Concept Complementary & Supplementary Two angles are complementary when they add to a right angle, and supplementary when they add to a straight angle. They need not be adjacent — only their measures matter. When to use: one angle is known and you need its partner: complement , supplement . Watch out for: C omplementary = C orner ( ); S upplementary = S traight ( ). Core Concept Vertical Angles & Linear Pairs

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