... ((PQCD) ị SPQCDPQCDaaVSSHa23.1151425105 3392714=== Ã Cú th dựng cụng thc t s th tớch: SPQCSPQCSABCSABCSPCDSPCDSACDSACDVSPSQVVaVSASBVSPVVaVSA.3 .3. .22445 ... Theo chng trỡnh chun Cõu VI .a: 1) C i xng vi A qua ng thng d ị C(3; 1). BDdABAD,5ỡẻớ==ợ ị B(2; 1), D(6; 5). 2) E ẻ (d2) ị E(3; 7; 6). PPddananaaa11,4(1;1;1)ỡ^ộựị== ... dId(,)52cos(,)2DDỡ=ùớ=ùợ ị abcabc2,1,101,2,10ộ==-=-ờ===-ở ị xyxy:2100:2100DDộ =ờ+-=ở. 2) Ly B ẻ (d1), C ẻ (d2). T : ABkAC=uuuruuur ị k12= ị B l trung im ca on thng AC. Ta cú th...