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| Math Central | Quandaries & Queries |
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Question from mary, a student: prove that the sum of the three angles inside any triangle always add up to 180 degrees? |
Hi Mary,
I drew a triangle ABC and extended the side BC to a point E. I then drew a line through C parallel to AB.
What does the fact that AB and DC tell you about the angles ABC, CAB, DCE and ACD?
Harley
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