C1 = A1 =E1 C2=E2 E1 = E2 suy ra C1 = C2 C1+ACE = 180 ( D C E thẳng(07) Save Image Image gallery: O%c2%a8o%c2%b7u%e2%80%a0u%e2%80%a1 O%c2%b7u%e2%80%9eus O%c2%b9o%c2%a8o%c2%b9o%c2%a8 A Story That Will Make You Question Everything