Complete the following indirect proof (proof by contradiction). Given: AABC Prove: A ABC has at most one obtuse angle Proof: First, we assume that this conclusion is false. In other words, we assume that the contrary statement "A ABC has Select One ? is ? This assumption does not state which angles are obtuse, but without loss of generality we can assume ZA and Z B are obtuse. That is, (1) m ZA ? . and (2) MLB ? V .. The third angle Z C satisfies m Z C > 0. Using (1)-(3) and addition properties of inequalities, we conclude that m ZA + m ZB + m ZC ? 180. But this contradicts the Select One ? v| which states that m ZA + m ZB + m ZC ?v 180. Therefore, the assumption made Is ? v, and the statement "A ABC has at most one obtuse angle" Is ? v