有两个函数f(x)=asin(kx+π/3),g(x)=bcos(2kx-π/3)(k>0),它们

有两个函数f(x)=asin(kx+π/3),g(x)=bcos(2kx-π/3)(k>0),它们
的周期之和为3π/2,且f(π/2)=g(π/2),f(π/4)=(-根号3)×g(π/4)+1.求k,a,b.
我和老虎在跳舞 1年前 已收到1个回答 举报

跨越_彩虹 幼苗

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T1+T2=2π/|k|+2π/|2k|=3π/k=3π/2k=2f(x)=asin(2x-π/3)g(x)=bcos(4x-π/6)f(π/2)=asin(2π/3)=asin(π-π/3)=asin(π/3)=acos(π/2-π/6)=acos(π/6)=g(π/2)=bcos(-π/6)=bcos(π/6)所以a=bf(π/4)=asin(π/6)=-√3g(π/4)-1=-√3bcos(5π/6)-1所以a/2=-√3*b(-√3/2)-1=3b/2-1a=3b-2a=b所以a=b=1f(x)=sin(2x-π/3)g(x)=cos(4x-π/6)

1年前

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