Proof: Angle180 90
Let's prove the following theorem:
if 180 = a + 90, then a = 90
Proof:
Given
1 | 180 = a + 90 |
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# | Claim | Reason |
---|---|---|
1 | 180 + (90 ⋅ (-1)) = a | if 180 = a + 90, then 180 + (90 ⋅ (-1)) = a |
2 | 180 + (90 ⋅ (-1)) = 90 | 180 + (90 ⋅ (-1)) = 90 |
3 | a = 90 | if 180 + (90 ⋅ (-1)) = a and 180 + (90 ⋅ (-1)) = 90, then a = 90 |
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