已知sin(π+α)=-1/2,计算(1)sin(π/2+α)(2)cos(α-3π/2)(3)tan(π/2-α)

问题描述:

已知sin(π+α)=-1/2,计算(1)sin(π/2+α)(2)cos(α-3π/2)(3)tan(π/2-α)

sin(π+α)=-1/2,sin(π/2+α)=sin(π+α-π/2)=-cos(π+α)=±√3/2;cos(α-3π/2)=cos(α-3π/2+2π)=cos(α+π/2)=cos(α+π-π/2)=sin(π+α)=-1/2tan(π/2-α)=-tan(α-π/2)=-tan(α+π-π/2...