2倍角公式
f(x)=cos^2(x-π/12)+sin^2(x+π/12)-1
=[cos(2x-π/6)+1]/2+[1-cos(2x+π/6)]/2-1
=1/2[cos(2x-π/6)-cos(2x+π/6)]
=1/2(√3/2cos2x+1/2sin2x-√3/2cos2x+1/2sin2x)
=1/2sin2x
周期是2π/2=π
f(x)=-f(-x)奇函数
2倍角公式
f(x)=cos^2(x-π/12)+sin^2(x+π/12)-1
=[cos(2x-π/6)+1]/2+[1-cos(2x+π/6)]/2-1
=1/2[cos(2x-π/6)-cos(2x+π/6)]
=1/2(√3/2cos2x+1/2sin2x-√3/2cos2x+1/2sin2x)
=1/2sin2x
周期是2π/2=π
f(x)=-f(-x)奇函数