已知f(α)=sin(π-α)cos(2π-α)/cos(-π-α)tanα,则f(-31/3π)的值为
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![已知f(α)=sin(π-α)cos(2π-α)/cos(-π-α)tanα,则f(-31/3π)的值为](/uploads/image/z/3709795-67-5.jpg?t=%E5%B7%B2%E7%9F%A5f%28%CE%B1%29%3Dsin%28%CF%80%EF%BC%8D%CE%B1%29cos%282%CF%80%EF%BC%8D%CE%B1%29%2Fcos%28%EF%BC%8D%CF%80%EF%BC%8D%CE%B1%29tan%CE%B1%2C%E5%88%99f%28%EF%BC%8D31%2F3%CF%80%29%E7%9A%84%E5%80%BC%E4%B8%BA)
已知f(α)=sin(π-α)cos(2π-α)/cos(-π-α)tanα,则f(-31/3π)的值为
已知f(α)=sin(π-α)cos(2π-α)/cos(-π-α)tanα,则f(-31/3π)的值为
已知f(α)=sin(π-α)cos(2π-α)/cos(-π-α)tanα,则f(-31/3π)的值为
∵f(α)=sinαcosα/-cosαtanα=-cosα
f(-31/3π)=)=-cos(10π+ π/3)==-cos(π /3)=-1/2