已知sin(α+β)=5sinβ,则tan(α+β)*cotα=sin(2α+β)=5sinβ,打错了

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已知sin(α+β)=5sinβ,则tan(α+β)*cotα=sin(2α+β)=5sinβ,打错了
已知sin(α+β)=5sinβ,则tan(α+β)*cotα=
sin(2α+β)=5sinβ,打错了

已知sin(α+β)=5sinβ,则tan(α+β)*cotα=sin(2α+β)=5sinβ,打错了
sin(α+β)=5sinβ
sinacosb+cosasinb=5sinb
sinacosb=sinb(5-cosa)
cosb=sinb(5-cosa)/sina
cos^2b+sin^2b=1=sin^2b[(5-cosa)^2/sin^2a+1]=sin^2b[(26-10cosa)/sin^2a]
sinb=+-sina/√(26-10cosa),cosb=+-(5-cosa)/√(26-10cosa)
tan(α+β)*cotα=sin(a+b)cosa/[cos(a+b)sina]=5sinbcosa/[cosacosb-sinasinb)sina
=[5sinacosa/√(26-10cosa)]/{[cosa(5-cosa)/√(26-10cosa)-sin^2a/√(26-10cosa)]sina}
=[5cosa]/[cosa(5-cosa)-sin^2a]
=5cosa/(5cosa-cos^2a-sin^2a)
=1+1/(5cosa-1)