1. Chapter 2
Segments and Angles

2. Section 4 Vertical Angles

3. Two angles are ______________________________ if they are not adjacent and their sides are formed by two intersecting lines. The scissors show two sets of vertical angles. Two adjacent angles are a ___________________________ if their noncommon sides are on the same line.

4. Example 1: Identify Vertical Angles and Linear Pairs Determine whether the labeled angles are vertical angles, a linear pair, or neither.

5. POSTULATE 7: Linear Pair Postulate Words: If two angles form a linear pair, then they are supplementary. Symbols: m<1 + m<2 = 180°

6. Example 2: Use the Linear Pair Postulate Find the measure of <RSU.

7. Theorem 2.3: Vertical Angles Theorem Words: Vertical angles are congruent. Symbols: <1 ≅ <3 and <2 ≅ <4

8. The following steps show you why the Vertical Angles Theorem is true.

9. Example 3: Use the Vertical Angles Theorem Find the measure of <CED.

10. Example 4: Find Angle Measures Find m<1, m<2, and m<3.

11. Checkpoint: Find Angle Measures Find m<1, m<2, and m<3.

12. Example 5: Use Algebra with Vertical Angles Find the value of y.

13. Checkpoint: Use Algebra with Angle Measures Find the value of the variable.