TRƯNG THCS Đ KIM TRA CHT LƯNG HỌC SINH GIỎI NĂM HỌC 2008 - 2009   !"#$ Bài 1:( 3 điểm) $%&'() ( ) ( ) *+ , - + * . , + - .  . + / , + 0. / 0 , 0 +, 0/ 1 *+,0 , 0*/ + 0. 2 0. − − = − + + $3456789:;<=>?@AB + + . + . + n n n n+ + − + − &C&D* Bài 2:(2 điểm) BxC  ( ) * / + .E+ . , , x − + = − + Bài 3: (2 điểm) 3D a c c b = 03456 + + + + a c a b c b + = + Bài 4: (3 điểm) 3D!&1F3E5<" &GF305>";&G&G1H=" I :D&DIJ103456 $13JIFK 13LLFI $M9NO" 5>13PO" 5>IF:D&D1NJI034 " NEEQ &$RIS EH BC⊥  ( ) H BC∈ 0FC ∠ TFIJ, D P ∠ IFJ+, D 0 ) ∠ TIK ∠ FI Lưu yU'< ∠ U'<V& TRƯNG THCS Đ,P ,N KIM TRA CHT LƯNG HSG MÔN TO,N 7 NĂM HỌC 2008 - 2009 Bài 1:." $ $*0," $ ( ) ( ) ( ) ( ) ( ) ( ) ( ) * *+ , - + * . , + *+ , *+ / * . / - . *+ - *+ ,  .  . .  . + / , *+ / * . *+ ,  . . * . *+ / *+ ,  . + 0. / 0 , 0 +, 0/ + 0. + 0. , 0 , 0 + 0. + 0. , 0 , 0+ 0 *+,0 , 0*/ + 0. 2 0. + 0. 0 . * , 0 0 *  + 0. 0 . * , 0 0 * + , 0 0 - + 0. 0+ + 0. 0/ , 0 0 * *  - . + A − − − − = − = − + + + + − − = − + + − = − − = − = $*0," $  + + . + . + n n n n+ + − + − J + + . . + + n n n n+ + + − − J + + . . *$ + + *$ n n + − + J * . * + , . * + * n n n n− × − × = × − × J*.  W+  $ 7X= + + . + . + n n n n+ + − + − M *K89:;<=>?@A0 Bài 2:+" $ ( ) * + . * + . *  + . . * , + . . * / + * / *- + .E+ . , , . , , , * / */ . , , * + . x x x x x x x x − = − =− = + = − =− + = − − + = − + ⇔ − + = + ⇔ − + =   ⇔ − = ⇔         ⇔  Bài 3: +" $ R a c c b = :<=5 + 0c a b= "V + + + + + + 0 0 a c a a b b c b a b + + = + +   J  $  $ a a b a b a b b + = + Bài 4:." $ a/*" $Y( AMC∆ K EMB∆ &V 1JI$  ∠ 13J ∠ IF";"Z$ FJ3$ > AMC∆ J EMB∆ &00&$ E,"  ⇒ 13JIF 7B AMC∆ J EMB∆ ⇒ ∠ 13J ∠ IF +V&&VK[5):D\5D"@]&^D_"@Q13KIF&`"@Q 1I$ a<=513LLFI0 b/*" $ Y( AMI∆ K EMK∆ &V 1JI$  ∠ 1NJ ∠ IKB AMC EMB∆ = ∆ $ 1NJI$ > AMI EMK∆ = ∆ &00&$ a<=5 ∠ 1NJ ∠ I  ∠ 1Nb ∠ NIJ*2 D )&HV&#c$ ⇒ ∠ Ib ∠ NIJ*2 D  ⇒ F" NPPQ c/*" $ 5D!&K<FTI ∠ TJ D $&V ∠ TFIJ, D ⇒ ∠ TIFJ D W ∠ TFIJ D W, D J/ D  ⇒ ∠ TIJ ∠ TIFW ∠ IFJ/ D W+, D J*, D   ∠ FIV&D^"Z&G HEM∆ > ∠ FIJ ∠ TIb ∠ TIJ*, D b D J*, D K H E M B A C I "[UV&D&G!&$ ( Hc sinh gii theo cch khc đng kt qu vn cho đim ti đa) . ,N KIM TRA CHT LƯNG HSG MÔN TO,N 7 NĂM HỌC 2008 - 2009 Bài 1:." $ $*0," $ ( ) ( ) ( ) ( ) ( ) ( ) ( ) * *+ , - + * . , + *+ , *+ / * . / - . *+ - *+ ,  .  . .  . +. GIỎI NĂM HỌC 2008 - 2009   !"#$ Bài 1:( 3 điểm) $%&'() ( ) ( ) *+ , - + * . , + - .  . + / , +. 0+ 0 *+,0 , 0*/ + 0. 2 0. + 0. 0 . * , 0 0 *  + 0. 0 . * , 0 0 * + , 0 0 - + 0. 0+ + 0. 0/ , 0 0 * *  - . + A − − − − = − = − + + + + − − = − + + − = − − = − = $*0," $  +