... VAA ' BDMN = VSABD - VSA ' MN V 7a = 32 0,25 1,0 Do a, b, c > v a + b + c = nờn a, b, c ẻ ( 0;1) 2 2 a - 2a + a a ( a - 1) Ta cú: = = -a + a 2 b +c 1- a ( -a Xột hm s + a ) + ( -b + b ) + ( - ... trung ủi m BC, h AH vuụng gúc v i AM BC AM Ta cú: BC ( AA ' M ) BC AH BC AA ' a M AH A ' M AH ( A ' BC ) AH = 1 a M t khỏc: = + AA ' = 2 AH A' A AM 3a KL: VABC A ' B ' C ' = 16 ... H thu c tia ủ i c a tia IA v IA = 2IH BC = AB = 2a ; AI= a ; IH= AH = AI + IH = 0,25 IA a = 2 3a K A B I H C Ta cú HC = AC + AH AC AH cos 45 HC = a 0,25 Vỡ SH ( ABC ) ( SC; ( ABC )) = SCH...