设tan(x+y)=2/5 ,cot[(3π/4)-y]=1/4 ,则(1+tanx)/(1-tanx)=?
问题描述:
设tan(x+y)=2/5 ,cot[(3π/4)-y]=1/4 ,则(1+tanx)/(1-tanx)=?
答
cot[(3π/4)-y]=1/4=tan(y-π/4).化简得tany=5/3.代入tan(x+y)=2/5.得tanx=-19/25.所以(1+tanx)/(1-tanx)=3/22.