sin^2 (π/12) -(1/2)=

sin^2 (π/12) -(1/2)= sin^ 2 π/12-1/3=? 1-2sin²π/8=sinπ/4 为什么sin-sin^2=1/4 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)= 求证:sin^2/(sin-cos) - (sin+cos)/(tan^2 -1) =sin+cos sin²0+sin²1+sin²2+……+sin²180= 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 sin((3π)/3-a)=sin(π+(1/2-a))=-(sin(1/2-a))＝-cosa sin(π/4+α)sin(π/4-α)=1/4 求2sin^2(a) -1+tana-1/tan 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) lim(n→∞) (1/n)[sin(π/n)+sin(2π/n)+…+sin(nπ/n)]=? 在△ABC中,求证；sin^(A/2)+sin^(B/2)+sin^(C/2)=1-2sin(A/2)sin(B/2)sin(C/2） f(x)=（1+cotx)sin^2x-2sin(x+π/4)sin(x-π/4)还有一题, 1-2sin²π/12 求sin²π/12-1/2