tan(a-π/4)=3,1/sinacosa=?guochen
问题描述：
tan(a-π/4)=3,1/sinacosa=?
guochen
答
tan(a-π/4)=3(tana-tanπ/4)/(1+tanatanπ/4)=3(tana-1)/(1+tana)=3tana-1=3+3tanatana=-2sina/cosa=tana=-2sina=-2cosa代入sin²a+cos²a=1cos²a=1/51/sinacosa=1/(-2cosa*cosa)=1/(-2cos²a)=-5...