sin(x+y)=?cos(x+y)=?tan(x+y)=?cot(x+y)=?sin2x=?cos2x=?tan2x=?cot2x=?
问题描述:
sin(x+y)=?cos(x+y)=?tan(x+y)=?cot(x+y)=?sin2x=?cos2x=?tan2x=?cot2x=?
答
sin(x+y)=sinxcosy+sinycosxcos(x+y)=cosxcosy-sinxsinytan(x+y)=(tanx+tany)/[1-tanxtany]cot(x+y)=(1-taxtany)/(tanx+tany)sin2x=2sinxcosxcos2x=cos²x-sin²xtan2x=2tanx/(1-tan²x)cot2x=(1-tan...