MTBT THCS Nam 2006

20 20 230 20 12,35 tan 30 25'.sin 23 30' . 3,06 .cot 15 45'.cos 35 20' A = 22 22 22 55 25 . 55 xy xy x y B xxyxxyxy æö + =+ ç÷ -+ + èø 22 222 2 12144 (2 ) 4 (2 ) 16 xxyy C xy x y xy x éù ++ =++´ êú + ëû x y (10 3 ) (10 3) 23 nn + 54756 15 n an=+ n n 13 22 x + 27 52 x + 20 47 ; 918 æö ç÷ èø 3 5; 2 æö ç÷ èø 125 36