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问题: 三角函数

化简
f(x)=2cosxsin(x+派/6)+cos^4x-sin^4x(都是4次方)

解答:

解:f(x)=2cosxsin(x+π/6)+cos^4x-sin^4x
````````=2cosx(√3·sinx/2+cosx/2)+(cos²x-sin²x)(cos²x+sin²x)
````````=√3·cosxsinx+cos²x+cos²x-sin²x
````````=√3·sin2x/2+2cos²x-sin²x
````````=√3·sin2x/2+cos2x+1-(1-cos2x)/2
````````=√3·sin2x/2+3cos2x/2+1/2
````````=√3·sin(2x+π/3)+1/2.