... 114114114; ;22 2+++++++++++++abbcabcbccaabccaaba+b+c Mt khỏc: 22 222 221 222 4 422 022 47=++ +-- -+ +++++abcabcabcabca 22 22( 1)(1)(1) 0-+ -+ -abc Tng t: 22 121 2 ;27 27++++++bcabcabc T ú suy ra: 22 2111444777++++++++++abbccaabc ... Attt111( 82; 6;10 )-+ +- ẻ d1, Bttt 222 ( ;2; 42 )-- + ẻ d2. ị ABtttttt2 121 21 (28 ;4) ;21 4) =-+ -- - +-uuur. ABi,(1;0;0)=uuurr cựng phng tttt2 121 4 021 40 -- -= ớ +-= ợ tt 122 218ỡ =- =ợ ị AB( 52; 16; 32) ,(18;16; 32 )-- -. ị Phng trỡnh ... Trn S Tựng 2) u (2; 1;1)D=-r. Gi H = d ầ D. Gi s Httt( 12; 1;) +-+ - ị MHttt (21 ;2; ) =-- -uuuur. MHuD^uuuurr ttt2 (21 ) (2) () 0-+ -- - = t23= ị duMH3(1;4 ;2) = =-- uuuurr ị d: xtytzt21 42 =+ù =- ù=ợ. Cõu...