... , ;| 6 4 | 4 3 3 3 3 3;5 50 1;0 , 0; 2t C D t d C AB CHt C D = = = = Vy ta ủ ca C v D l 5 8 8 2; , ;3 3 3 3C D hoc ( ) ( )1;0 , 0; 2C D 0.25 ... ;I d y x I t t = . I l trung ủim ca AC v BD nờn ta cú: ( ) ( )2 1;2 , 2 ;2 2C t t D t t . 0.5 Mt khỏc: D . 4 ABCS AB CH= = (CH: chiu cao) 4 5CH = . Ngoi ra: ( )( ) ( ) 4 5 ... )( 4 Zkkx +=(tm) ( ) 4 0;0== xkx KL: 0. 5 Cõu IV Tớnh tớch phõn : 220I cos cos2x xdx= 1 2 2 220 0 01 1I cos cos2 (1 cos 2 )cos 2 (1 2cos 2 cos 4 )2 4 x xdx x xdx...