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中等数学几种公式的记忆方法 对学生来说,数学公式的推导固然重要,但牢固地记忆公式更有其实用价值。然而有些公式时间长了学生易忘,用起来就不那么得心应手。因此对常用而又不易记住的公式,师生应该共同研制一些行之有效的特殊记法。现举本人采用的几例特殊记法,以供读者参考。1 三倍角公式 sin3a=3sina-4sin~3a cos3a=4cos~3a-3cosa 这两个公式的右端,都等于以角a为自变量,与左端函数同名的两个函数之差。但其系数、指数容易混淆。 记法:“三四、四三,三不重”。
The memory method of several formulas of medium mathematics To the student, the derivation of the mathematical formula is important, but remembering the formula firmly has more practical value. However, some formulas are long forgotten by the students and are less handy to use. Therefore, common and not easy to remember the formula, teachers and students should jointly develop some effective special notation. I now use a few special notes, for readers reference. 1 The triple angle formula sin3a = 3sina-4sin ~ 3a cos3a = 4cos ~ 3a-3cosa The right end of both formulas are equal to the difference between the two functions with the same name as the left end function with the angle a as the independent variable. But its coefficient, index easily confused. Note: “three four, four three, three not heavy.”