已知f(α)=2tanα-(2sin^2α/2-1)/(sinα/2cosα/2),求f(π/12)
问题描述：
已知f(α)=2tanα-(2sin^2α/2-1)/(sinα/2cosα/2),求f(π/12)
答
f(a)=2tana-(2sin^2a/2-1)/[(1/2)sina]=2tana-（1-cosa-1)/[(1/2)sina]=2tana+2cosa/sina=2tana+2ctgacos30 °= √3/2 cos15 °= √[(1 + cos30° )/2] sin15° = √[(1 - cos30° )/2] tan15° = sin15° /cos15° ...