sin(π/6-α)=1/5,则sin(5π/6+α)=?上课没听懂

已知sinα（x+π/6）=1/4,则sin（5π/6-x）+sin（π/3-x）的平方=? sin(π/6-α)=1/4,则sin(π/6+2α)= sin(π/6-α)=1/5,则sin(5π/6+α)=?上课没听懂 设角a=-35π/6,则2sin(π+α)cos(π-α)-cos(π+α)/ 1+sin^2α+sin(π-α)-cos^2(π+α)sina=sin(-35π/6)=sin(-6π+π/6)=1/2 cosα=根号3/22sin(π＋α)cos(π-α)-cos(π+α)/ [1+sin^2α+sin(π-α)-cos^2(π+α)]=2（-sinα)(-cosα）+cosα/[1+sin² sinα为第一象限角sinα=5分之3求sin(α+6分之π) 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) 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? 2sinα-3cosα/4sinα-9cosα=-1,则9sin^2α-3sinαcosα-5= sin0=0 sin(1/6π)=1/2sin(1/3π)=√3/2sin(1/2π)=1sin(2/3π)=√3/2sin(5/6π)=1/2sin(π)=0sin(-π)=0sin(-5/6π)=-1/2sin(-2/3π)=-√3/2sin(-1/2π)=-1sin(-1/3π)=-√3/2sin(-1/6π)=-1/2sin(7/6π)=-1/2sin(4/3π)=-√3/2sin(5/3π)=-√3/2sin(11/6π)=-1/ 1.sin^2(1°)+sin^2(2°)+sin^2(3°)+……+sin^2(89°)+sin^2(90°).2.已知tanα100°=k,则sin80°=_______?3.已知α是锐角,2tan(π-α)-3cos(π/2+β)+5=0,tan(π+α)+6sin(π+β)-1=0.则sinα=______? 已知α,β∈(0,π/2),且2tanα+3sinβ=7,tanα-6sinβ=1,则sinα= sin(π-α)=-2sin(π/2+α),则sinαcosα等于 已知sin(3π-α)=-2sin(π/2+α)则sinαcosα Sin（5π+α)=sin(π+α)=-sinα正确吗? 已知sin(x+π/6)=1/3,则sin(5π/6-x)+sin平方(π/3-x)的值是, 已知3sin²α+2sin²β=2sinα,求cos²α+cos²β的取值范围已知3sin²α+2sin²β=2sinα则有2sin²β=2sinα-3sin²α即sin²β=sinα-1.5sin²α所以cos²β=1-sin²β=1-(sinα-1.5sin²α)=1-