3 2
< 1 and 2 2 are vertical angles
23 and 24 are vertical angles
How do you know that vertical angles are congruent?
m21+ m23 = 180° because the Linear Pair postulate
m22 + m23 = 180° because the Linear Pair postulate
Set the two equations equal to each other since they both equal 180 degrees.
m22+ m23 = m_1 + m23
-m23
-m23
m2 = m_1
Therefore: 22 =21
1. Prove that 23 224 using a similar method.