1. Write a two-column proof
EXAMPLE 1
Write a two-column proof
Write a two-column proof for the situation in Example 4 on page 107.
GIVEN:
m∠ 1 = m∠ 3
PROVE:
m∠ EBA = m∠ DBC
STATEMENT
REASONS 1.
m∠ 1 = m∠ 3 1.
Given 2.
m∠ EBA = m∠ m∠ 2 2.
Angle Addition Postulate 3.
m∠ EBA = m∠ m∠ 2 3.
Substitution Property of Equality

2. Write a two-column proof
EXAMPLE 1
Write a two-column proof 4.
m∠ m∠ 2 = m∠ DBC 4.
Angle Addition Postulate 5.
m∠ EBA = m∠ DBC 5.
Transitive Property of Equality

3. GUIDED PRACTICE for Example 1
1. Four steps of a proof are shown. Give the reasons for the last two steps.
GIVEN : AC = AB + AB
PROVE : AB = BC
STATEMENT
REASONS 1.
AC = AB + AB 1.
Given 2.
AB + BC = AC 2.
Segment Addition Postulate 3.
AB + AB = AB + BC 3. ? 4.
AB = BC 4. ?

4. GUIDED PRACTICE for Example 1 ANSWER GIVEN : AC = AB + AB
PROVE : AB = BC
ANSWER 1.
AC = AB + AB 2.
AB + BC = AC 3.
AB + AB = AB + BC 4.
AB = BC
Given
Segment Addition Postulate
Transitive Property of Equality
Subtraction Property of Equality
STATEMENT
REASONS