高一数学公式

tan(x+y)=sin(x+y)/cos(x+y)=sinxcosy+sinycosx/cosxcosysinxsiny=tanx+tany/1tanxtany；tan(xy)=sin(xy)/cos(xy)=sinxcosysinycosx/cosxcosy+sinxsiny=tanxtany/1+tanxtany。