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Cos12分之派等于多少

(cos12分之派-sin12分之派)(cos12分之派+sin12分之派) =(cos12分之派)平方-(sin12分之派)平方 =cos6分之派=(√3)/2

0.9999895609

使用公式cos(15')=cos45'cos30'+sin45'sin30'

解:cos(17π/12)=cos(π+5π/12)=-cos(5π/12)=-cos75°=-cos(30°+45°)=-cos30°cos45°+sin30°sin45°=(√2-√6)/4

cosπ/12=cos15°=cos(45°-30°) =cos45°cos30°+sin45°sin30°=(根号6+根号2)/4

公式:2sinxcosx=sin2x所以:sinxcosx=(sin2x)/2所以,sinπ/12cosπ/12=(sinπ/6)/2=1/4

sin(π/12)-√3cos(π/12)=2sin(π/12-π/3)=2sin(-π/4)=-√2

sin12分之π*cos12分之π=1/2*sin(2*12分之π)=1/2*sin6分之π=1/2*1/2=1/4

B. 根号2(√3)sin(π/12) + cos(π/12)=[cos(π/6)/sin(π/6)]sin(π/12) + cos(π/12)=[cos(π/6)sin(π/12) + cos(π/12)sin(π/6)]/sin(π/6)=sin(π/6+π/12)/(1/2)=2sin(π/4)=√2

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