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公式若注意其特点,巧解妙证一些题,真是别有情趣。例1 求函数f(x)=1-cos2x+1+cos2x~(1/2)的最小正周期。解由(＊)得解由a在二象限知sina>0, cosa<0 由(＊)得原式=2+2cosa~(1/2)+1-sina~(1/2)-1+sina~(1/2)
If the formula pays attention to its characteristics, it is true that there are some problems in solving the subtlety certificate. Example 1 Find the minimum positive period of the function f(x)=1-cos2x+1+cos2x~(1/2). Solution from (*) solution from a in the two-quadrant sina>0, cosa<0 from (*) to the original formula=2+2cosa~(1/2)+1-sina~(1/2)-1+ Sina~(1/2)