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在求解一些数学问题中,特别是涉及一些三角形的问题时,经常要通过作垂线来辅助解题.但在作垂线的过程中,垂足的位置却往往不能确定,也由此会产生对三角形是锐角或者是钝角的讨论.在《人教版》必修5第一章“解三角形”第1节对正弦定理的推导中就分锐角三角形和钝角三角形进行分类讨论,尽管垂足的位置不影响定理的成立,但它又恰恰能给解题者带来一些麻烦.那么,能不能仅通过一种情形的分析,就能解决问
In solving some mathematical problems, especially those involving some triangles, we often make a solution to the problem by making perpendiculars.However, in the process of making vertical lines, the position of foot-dropping can not always be determined, which leads to A discussion of whether an acute or obtuse triangle is a triangle is divided into acute triangles and obtuse triangles in the derivation of the sine theorem in Chapter 1, "The Triangle of Comprehension, The position does not affect the establishment of the theorem, but it can also bring some problems to the solver.However, can only be through a case analysis, can solve the problem