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题目已知25cosA+5sinB+tanC=0,且sin2B-4cosAtanC=0,求证:tanC=25cosA.《中学生数学》2004年11月上期魏鑫同学联想到一元二次方程巧证了该题.笔者构造数列模型,也可得简巧证.证明由已知得
The topic is known as 25cosA+5sinB+tanC=0, and sin2B-4cosAtanC=0. Proof: tanC=25cosA. “Middle-school mathematics” In the last period of November 2004, Wei Xin’s student thought of a one-dimensional quadratic equation to prove the problem. The sequence model can also be easily verified. The proof is known