求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值
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![求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值](/uploads/image/z/5197664-56-4.jpg?t=%E6%B1%82cos8%C2%B0-sin7%C2%B0%C3%97sin15%C2%B0%E5%88%86%E4%B9%8Bsin8%C2%B0%2Bsin7%C2%B0cos15%C2%B0%E7%9A%84%E5%80%BC)
求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值
求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值
求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值
(sin(15-7)+sin7cos15)/(cos(15-7)-sin7sin15)
=(sin(15)cos(7)-cos(15)sin(7)+)+sin7cos15))/cos(15)cos(7)+sin(15)sin(7)-sin7sin15)
=sin(15)cos(7)/cos(15)cos(7)
=tan(15)
=tan(45-30)=(tan45-tan30)/(1+tan45*tan30)=0.26795.
用计算机算,这些都不是特殊角度,没办法化简结果的