2 of 17 Given: Intersecting lines and m
as shown below.
m
Prove: 2123
3
Reasons
1. Given
2. Linear Pair of Angles
Proof:
Statements
1. Two intersecting lines
21 and 22 are supplementary
2.
22 and 23 are supplementary
mZ1 + Z2 = 180
3.
mZ3+ m2 = 180
4. Z1 + Z2 = 22 +23
5. mZ1 + Z2 = m2+ m23
6. mZ1 =m23
7. 21:23
3. ?
4. Transitive
5. Substitution
6. Subtraction property of equality
7. Definition of congruence
Which reason could be used to justify Statement 3 in this proof?
A. subtraction property of equality
B. substitution property of equality
C. definition of supplementary
D. definition of complementary