sin^ 2 π/12-1/3=?

sin^ 2 π/12-1/3=? 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)= 傅里叶级数作图f（x）=2sin[x] - sin[2x] + 2/3sin[3x] - 1/2sin[4x]我用mathematica输入程序Plot[{2sin[x],-2sin[x],2sin[x] - sin[2x],-2sin[x] + sin[2x],2sin[x] - sin[2x] + 2/3sin[3x],-2sin[x] + sin[2x] - 2/3sin[3x],2sin[x] - sin[2x] + 2/3si 已知sin(x+π/6)=1/3,求sin(5π/6-x)+sin^2(π/3-x) sin((3π)/3-a)=sin(π+(1/2-a))=-(sin(1/2-a))＝-cosa sin^2 (π/12) -(1/2)= 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2(π/3-x) sin²1°+sin²2°+sin²3°+……+sin²87°+sin²88°+sin²89°= sin²1°+sin²2°+sin²3°+...+sin²88°+sin²89°+sin²90°=等于多少? 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/ 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. 1-2sin²π/8=sinπ/4 2sin(α+π/3）=sinα+______ 2sin π/6 =sin π/3,吗,求解释,还有-sin π/6=sin- π/6吗 ①利用公式sin(π-θ)=sinθ和sin(∏+θ)=-sinθ证明：sin（-θ）=-sinθ②证明tanθsinθ∕tanθ-sinθ=1+cosθ∕sinθ③已知sinα-2cosα+1=0,α≠kπ+π∕2,k∈z求：tan（3π-α）和1∕sin2α-sinαcosα+1的值‍ sin²1°+sin²2°+sin²3°+.+sin²89°= -1为什么? 已知sin(α+β)*sin(α-β)=-1/3,求sin^2α-sin^2β的值