已知cos(α+5π/12)=1/3,且-π

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已知cos(α+5π/12)=1/3,且-π已知cos(α+5π/12)=1/3,且-π已知cos(α+5π/12)=1/3,且-π-π-π+5π/12-7π/12cos(α+5π/12)=1/3-π

已知cos(α+5π/12)=1/3,且-π
已知cos(α+5π/12)=1/3,且-π

已知cos(α+5π/12)=1/3,且-π
-π<α<-π/2,
-π+5π/12<α+5π/12<-π/2+5π/12
-7π/12<α+5π/12<-π/12
cos(α+5π/12)=1/3
-π/2<α+5π/12<-π/12
cos(π/12-α)
=cos[(π/2-5π/12)-α]
=cos[π/2-(5π/12+α)]
=sin(5π/12+α)
=-2√2/3
cos(7π/12-α)
=cos[(π-5π/12)-α]
=cos[π-(5π/12+α)]
=-cos(α+5π/12)
=-1/3
cos(α+17π/12)
=cos(π+α+5π/12)
=-cos(α+5π/12)
=-1/3

已知cos(α+5π/12)=1/3,且-π 已知sinα-cosα=1/5,且π 已知cosα=1/3,且-π/2 已知cos(α+β)=3/5,cos(α-β)=12/13,且0 已知cosα=3/5,cos(α-β)=12/13,且0 已知sin(α+β)=-3/5 ,cos(α-β)=12/13,且π/2 已知sinα+cosα=-1/5,且2π/3 已知cos(5π/12 +a）=1/3 且-π 已知cos(5π/12+a)=1/3,且-π 已知cos(5л/12+α)=1/3,且-л 已知cos（5π/12+a）=1/3,且-《a《-π/2,则cos（π/12—a）等于?是：且-π《a《-π/2 已知α为钝角,且sin(α+π/12)=1/3cos(α+5π/12)=? 已知sinα-cosα=1/2,且π 已知cos α=-（12/13）,且π 已知cosα=-12/13,且π/2 已知sinα+cosα=1/5,且0 已知sinα+cosα=1/3,且0 已知cosθ=-3/5,且π