sin(5π/6-α)+sin(5π /6+α)=cosα 证明等式恒成立

Sin（5π+α)=sin(π+α)=-sinα正确吗? sinα为第一象限角sinα=5分之3求sin(α+6分之π) 计算,sin(π/12)-sin(5π/12)+2sin(π/8)sin(3π/8) sin(α+π/6)=-4/5,α属于（-π/2,π/2),求sinα 若α∈(π/2,π),sin(α+π/6)=3/5,sinα= 利用和差角公式化简 (2)sin(π/3+α)+sin(π/3-α)(2)sin(π/3+α)+sin(π/3-α)(3)cos(π/4+α)-cos(π/4-α)(4)cos(60°+α)+cos(60°-α)(5)sin(α-β)cosβ+cos(α-β)sinβ(6)cos(α+β)cosβ+sin(α+β)sinβ sin(5π+π/2+α) 已知sin(x+π/6)=1/3,求sin(5π/6-x)+sin^2(π/3-x) 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2(π/3-x) 化简sin(4π-a)*sin(5π-a)=? sinα=4/5,π/2 sin（5π-α） 等于什么? 若（sinα+cosα）/（sinα-cosα）=2 则sin(α-5π)·sin(3π/2-α)=? 若sinα+cosα/sinα-cosα=2,则sin(α-5π）*sin（3π/2-α）等于? 若(sinα+cosα)/(sinα-cosα)=2,求sin(α-5π)sin(3π/2-α)的值 sin(-5π/3)等于 sin(5π/12)= sin(-5π/12)是多少