The butterfly theorem revisited - Nikolas Dergiades and Sung Hyun Lim We start with a proof of the original butterfly theorem, give without proof Mackay's generalization, and finally prove a full generalization of these two versions of the butterfly theorem. ✪ ✪ ✪ ✪ ✪ Link tải tài liệu: LINK TẢI TÀI LIỆU Theo LTTK Education