- #1
Mr Davis 97
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So I am working on this simple proof, but am confused about the term "external angle." The problem says that if ##a##, ##b##, and ##c## are external angles to a triangle, then ##a + b + c = 360##. However, is seems that the vertex of each triangle has two possible external angles, since there are two line segments that converge to that point (the vertex). So this would mean that there are 6 possible external angles for the triangle. So when it says to sum 3 of them, I'm not sure which ones, or how.