Sin(α + π/3)+Sinα =sinαcosπ/3+cosαsinπ/3+Sinα =(3Sinα)/2+(√3cosα)/2=√3(√3sinα/2+cosα/2) =√3sin(α+π/6)=-4√3/5 sin(α+π/6)=-4/5<0 -π/2〈α〈0,-π/3〈α+π/6〈π/6,-π/3〈α+π/6〈0 cos(α+π/6)=3/5 Cosα=Cos(α+π/6-π/6)=c0s(α+π/6)cosπ/6+sin(α+π/6)sinπ/6 =(3/5)(√3/2)+(-4/5)(1/2)==(3√3-4)/10
答：已知sin(α-3π)=2cos(α-4π),求[sin(π-α)+5cos(2π-α)]/[2cos(π-α)-sin(-α)] 的值 解: sin(α-3π...详情>>
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