求sin(π/14)*sin(3π/14)*sin(5π/14)的值

求sin(π/14)*sin(3π/14)*sin(5π/14)的值 2sin π/6 =sin π/3,吗,求解释,还有-sin π/6=sin- π/6吗 求sin^2α+sin^2(π/3 +α)+sin^2(π/3 -α) 已知sinα=-0.4,求下列三角函数值 sin（-α） sin（3π-α） sin（α-π） sin（α-10π） sin(-π/3）求过程 sin(-π/3) 计算,sin(π/12)-sin(5π/12)+2sin(π/8)sin(3π/8) 化简sin(α+β)+sin(α-β)+2sinαsin(3π/2-β)= 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) 已知sin(3π+a)=2sin[(3π/2)+a],求sin^2a+sin2a的值 sinα为第一象限角sinα=5分之3求sin(α+6分之π) 求Sin(π+π/6)Sin(2π+π/6)Sin(3π+π/6).Sin(2008π+π/6)的值 令n趋近于无穷大,且n存在,求sin(π/n)+sin(2π/n)+sin(3π/n)+...+sin(π)=?. sin（-19π/6）=?已知[3Sin(π+a)+Cos(π-a)]/4Sin(-a)-Sin(5π/2+a)=2，求tan a 三角形ABC是锐角三角形,sin²A=sin(π/3+B)sin(π/3-B)+sin²B,求角A 若(sinα+cosα)/(sinα-cosα)=2,求sin(α-5π)sin(3π/2-α)的值 设α,β,γ∈(0,π/2)且(sinα)^2+(sinβ)^2+(sinγ)^2=1求函数y=(sinα)^3/sinβ+(sinβ)^3/sinγ+(sinγ)^3/sinα 的最小值.