cho tam giac IHK co cac diem E,F,G lan luot la trung diem cua cac canh HI,HK,IK
a) Chung to cac doan thang EF,FG,GE chia tam giac IHK thanh 4 phan co dien tich bang nhau .
b) Biet rang cac doan HG,IF,KE cat nhau tai Q . Chung to rang doan HQ gap doi doan QG.