# CCGPS AG 1.8.1 Example 4

- Author:
- Walch Education

- Topic:
- Angles, Straight Lines

Prove that vertical angles are congruent given a pair of intersecting lines, and .

- Draw a diagram and label three adjacent angles.
- Start with the Supplement Theorem.
- Use substitution.
- Use the Reflexive Property.
- Use the Subtraction Property.
- Use the definition of congruence.

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