Cho hbh ABCD (AB>AD). Tren canh AB lay diem M tuy y sao cho AM >MB va M khong trung voi diem A,B. Duong thang MC keo dai cat AD tai N,duong thang NB cat DC tai P.
a.Chung minh \(\Delta\)NDC dong dang voi \(\Delta\)CBM
b. Chung minh PC.PN=PB.PD
c.Noi DB cat NC tai E. Chung minh:\(^{CE^2}\)=EM.EN(nhanh nhe)