已知sin(π/3 -α)=1/5求sin(2π/3 +α)和cos(7π/6 +α)的值2.已知sinβ=3/5,sin(α-β)=1,求cosα的值

问题描述:

已知sin(π/3 -α)=1/5求sin(2π/3 +α)和cos(7π/6 +α)的值
2.已知sinβ=3/5,sin(α-β)=1,求cosα的值