在三角形ABC中,abc为角ABC的对边,a=2倍根号3,tan(A+B)/2+tanC/2=4,sinBsinC=cos^2（A/2）求A.B和b,c
问题描述：
在三角形ABC中,abc为角ABC的对边,a=2倍根号3,tan(A+B)/2+tanC/2=4,sinBsinC=cos^2（A/2）求A.B和b,c
答
tan(A+B)/2+tanC/2=4,tan(A+B)＝tan(π-C)所以,tan(A+B)/2+tanC/2= tan(π-C)/2+tanC/2= cotC/2 + tanC/2= (cosC/2)/(sinC/2) +(sinC/2)/(cosC/2)＝ 2/(sinC)＝ 4sinC＝1/2,C＝π/6,或C＝5π/6cosA/2=cos(π-B-C)/2=...