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最佳答案:一、对二、cos(kπ-α)=-cosα不对,当k为偶数时,cos(kπ-α)=cos(2nπ-α)=cosα当k为奇数时,cos(kπ-α)=cos(2nπ+
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最佳答案:sin(-16π/3)=-sin(16π/3)=-sin(4π+4π/3)=-sin(4π/3)=-sin(π+π/3)=sin(π/3)=根号3/2常用的诱导
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最佳答案:cos(-61π/12)=cos(6π-11π/12)=cos(-11π/12)=-cos15度=-cos(60-45)=-(cos60cos45+sin60s
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最佳答案:cos(61π/12)=cos(π/12)=cos(π/3-π4)=(√2+√6)/4tan(35π/12)=tan(11π/12)=-tan(π/12)=-(
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最佳答案:类似吧.还有比如说x²+y²=1,则可以令x=sinα,y=cosα这类技巧.
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最佳答案:sin(-7π/12)= -sin(7π/12)= -sin﹙π/3+π/4﹚= -(sinπ/3cosπ/4+cosπ/3sinπ/4)= -(√3/2 *
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最佳答案:cos65π/6=cos(65π/6-10π)=cos(5π/6)=cos(π-π/6)=-cosπ/6=-√3/2sin(-31π/4)=sin(-31π/4