已知(tgA+1)/(1-tgA)=3+2根号2 求sinA和cosA
问题描述：
已知(tgA+1)/(1-tgA)=3+2根号2 求sinA和cosA
答
(tgA+1)/(1-tgA)=3+2根号2
=>tgA+1=(3+2根号2)*(1-tgA)
=>tgA+1=3-3tgA+2根号2-2根号2tgA
=>2tgA+2根号2tgA=2+2根号2
=>(2+2根号2)tgA=2+2根号2
=>tgA=1
即sinA=cosA
sinA=cosA=(根号2)/2