... nhien cua t~p ph\! thuQchàm sau: (0 .75 d) = {AB7 BC, AB7 ADF, F7 GH, G7IK, G LG} Ta có: AB7 BC => AB7 C AB7 ADF =;>AB7 DF => AB7 CDF (1) F G7LG=>G7L G7lK => G7lKL (2) (O.25d) Tir (1) (2), ta có ... sau: F = {AB7 C, AB7 D, B7 DE, CD7EK, CE7GH, G7AC} Chírng minh ring: AB E AB G (0 .75 d) Ta có: AB C & AB D => AB CD CD EK => AB E (dpcm) (0 .75 d) Ta có: AB C & AB E => AB CE CE GH => AB7 G (dpcm) ... G7LG=>G7L G7lK => G7lKL (2) (O.25d) Tir (1) (2), ta có t~p ptb rút gQn tt,r nhien F ,Ç~ = { AB7 CDF, F7 GH, G7lKL } (2.0di~m): xét quanh~ sau: KETQUA(MASV MAHM, HOTEN, PHAI, MALOP, TENLOP, BIEMTHI)...