Proof: Right Angle Reverse
Let's prove the following theorem:
if ∠ABC is a right angle, then ∠CBA is a right angle
Proof:
Given
| 1 | ∠ABC is a right angle |
|---|
| # | Claim | Reason |
|---|---|---|
| 1 | m∠ABC = 90 | if ∠ABC is a right angle, then m∠ABC = 90 |
| 2 | m∠ABC = m∠CBA | m∠ABC = m∠CBA |
| 3 | m∠CBA = 90 | if m∠ABC = m∠CBA and m∠ABC = 90, then m∠CBA = 90 |
| 4 | ∠CBA is a right angle | if m∠CBA = 90, then ∠CBA is a right angle |
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