已知cos(x-派/6)=-根号3/3,则cosx+cos(x-派/3)的值是
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![已知cos(x-派/6)=-根号3/3,则cosx+cos(x-派/3)的值是](/uploads/image/z/5265299-11-9.jpg?t=%E5%B7%B2%E7%9F%A5cos%28x-%E6%B4%BE%2F6%29%3D-%E6%A0%B9%E5%8F%B73%2F3%2C%E5%88%99cosx%2Bcos%28x-%E6%B4%BE%2F3%29%E7%9A%84%E5%80%BC%E6%98%AF)
已知cos(x-派/6)=-根号3/3,则cosx+cos(x-派/3)的值是
已知cos(x-派/6)=-根号3/3,则cosx+cos(x-派/3)的值是
已知cos(x-派/6)=-根号3/3,则cosx+cos(x-派/3)的值是
cosx+cos(x-派/3)
=2cos(2x-π/3)/2cos(x-x+π/3)/2
=2cos(x-π/6)×cosπ/6
=2×(-√3/3)×√3/2
=-1