Angle Relationships
Understand complementary, supplementary, vertical, and parallel line angles.
Practice Problems
Supplementary: 3x and 2x
Parallel lines, one angle 110°
Pro Tips & Shortcuts
SAT Tip: Complementary = Corner (90° like a corner). Supplementary = Straight (180° like a line).
SAT Tip: Vertical angles are one of the most tested angle relationships on the SAT.
SAT Tip: Look for parallel line markings (arrows) to identify these relationships.
SAT Tip: Set up an equation using the angle relationship.
SAT Tip: When you see parallel lines, look for equal angles and supplementary pairs.
If one angle is x, its complement is 90-x, its supplement is 180-x.
If you see an X formed by two lines, opposite angles are equal.
Corresponding angles are in the same position at each intersection.
Check: 3(36) + 2(36) = 108 + 72 = 180 ✓
Many angles will be 110° or 70° (supplement) in this diagram.