1、BA 垂直于MN,BA=3,即△ABC的边长=3 2、AE=1*t/配拍亏2 S=t/贺锋2*t/2*√3 /2=√3t /8 (0<=t<=3)3、 PE=3-2t EF=√培神3t/2t=6/(4+√3)when3>= t>=1.5PE=2*(t-1.5)PF=3-2(t-1.5)t=9/4