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用课本上介绍的两个公式sin3α=3sinα-4sin~3α和“在△ABC中,有a=bcosC+ccosB”(后者叫做射影定理)可以给出几道高考题或竞赛题的简解.
Using the two equations introduced in the textbook, sin3α = 3sinα-4sin ~ 3α and “In △ ABC, there is a = bcosC + ccosB” (the latter is called projective theorem) solution.