化简sin15°-cos15°/sin15°+cos15°

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化简sin15°-cos15°/sin15°+cos15°
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化简sin15°-cos15°/sin15°+cos15°
化简sin15°-cos15°/sin15°+cos15°

化简sin15°-cos15°/sin15°+cos15°
sin15°-cos15°/sin15°+cos15°
=tan15°-1 / tan15°+1
=tan15°-tan45° / tan15°+1
=tan(15°-45°)
=-tan30°
=-√3/3

=(1/2)*2sin15°*cos15°
=(1/2)*sin(15°+15°)
=(1/2)*sin30°
=(1/2)*(1/2)
=1/4

把sin15看做sin(45-30),把cos15看做cos(45-30),再根据和差公式计算就可以了