sin(π-α)=-2sin(π/2+α),求sinα·cosα
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sin(π-α)=-2sin(π/2+α),求sinα·cosα
sin(π-α)=-2sin(π/2+α),求sinα·cosα
sin(π-α)=-2sin(π/2+α),求sinα·cosα
化简sin(π-α)=-2sin(π/2+α),得sinα=-2cosα.
再联立(sinα)^2+(cosα)^2=1,求出(cosα)^2=1/5
sinα·cosα=-2(cosα)^2=-2/5
化简sin(α+β)+sin(α-β)+2sinαsin(3π/2-β)=
2sin(α+π/3)=sinα+______
为什么sin(2π-α)=-sinα?
sin(π-α)=-2sin(π/2+α),则sinαcosα等于
sin(π-α)=-2sin(π/2+α),求sinα·cosα
已知sin(3π-α)=-2sin(π/2+α)则sinαcosα
求证:sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα
求证sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα
求证sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα
求证sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα
证明:sin(2α+β)/sinα - 2cos(α+β)=sinβ/sinα
化简sin^2(α-π/6)+sin^2(α+π/6)-sin^2α
求sin^2α+sin^2(π/3 +α)+sin^2(π/3 -α)
求值sin^2(α-π/6)+sin^2(α+π/6)-sin^2α
sin(α+β)sin(α-β)=sin^2α-sin^2β的推导过程
若sin^2β-sin^2α=m,则sin(α+β)sin(α-β)
1.证明 cos(α-π/2)=sinα sin(α-π/2)=﹣sinαcos(α-π/2)=sinαsin(α-π/2)=﹣sinα
sin(3∏-α)=-2sin(Π∕2+α)则sinαcosα等于