tan15°+cos15°/sin15°的值 求详解

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tan15°+cos15°/sin15°的值 求详解

tan15°+cos15°/sin15°的值 求详解
tan15°+cos15°/sin15°的值 求详解

tan15°+cos15°/sin15°的值 求详解
tan15°+cos15°/sin15°=sin15°/cos15°+cos15°/sin15°
(sin15°)^2+(cos15°)^2 1 1 1
=-------------------------------=-----------------------=-----------------=------------------=4
sin15°cos15° sin(2*15° )/2 sin(30° )/2 (1/2)/2
(sin2α=2sinαcosα)

我的错了

tan15°+cos15°/sin15°
=sin15°/cos15°+cos15°/sin15° (通分)
=(sin²15+cos²15)/sin15cos15
=1/(0.5*2sin15cos15)
=1/(0.5*sin30)
=1/(0.5*0.5)
=4