7th Grade · Geometry
Vertical Angles
7.G.B.5
Definition
The pair of non-adjacent angles formed when two lines intersect. Vertical angles are always congruent (equal in measure).
Examples
- If ∠1 = 65°, then ∠3 (its vertical angle) = 65° too.
- ∠2 = 180° - 65° = 115° (linear pair with ∠1).
Key rule
Vertical angles are formed across from each other at an intersection and are always equal.
Memory hook
Angles across the X from each other match.