1、1 1. A B a b c a 2 +b 2 =c 2 C D 2. A a b 3-a 3-b B ab=0 a=0 b =0 C D 60 3. _ 4. x 3 2x-1 A 11 B 11 8 C 11 8 5 D x 5. ABC AB=AC BD =BC AD=DE=BE A A 22 .5 B 35 C 45 D 55 A B C D E2 6. ABC AB=AC BAD= AE=AD EDC= A 1 2 B 1 3 C 1 4 D 1 5 7. AOB=60 P OA OP =10 M N OB PM=PN MN=2 OM _ 8. ABC ABC ACB BO CO O
2、 AO O EF BC AB AC E F AB =5 AC =4 1 AEF 2 O BC 1 OAB A B C D E A B O M N P A B C O F E3 9. ABC AB=BC BE AC E AD BC D BAD=45 AD BE F CF 1 BF=2AE 2 2 CD AD 10. ABC 11. A B C D A B C D E F 2x x A B C4 12. ABC C=90 DE B A CAD: BAD=5:2 CDA A 20 B 40 C 50 D 70 13. ABC D E AB BC AD=BE AE CD F AG CD G FG AF
3、 =_ 13 14 14. ABC DE A BC P DP BC BP=4 cm AD A 5 cm B 3 cm C 43 cm D 4 cm 15. ABC C=90 B =30 AD BAC DE AB E 1 CD=3 cm AB 2 AB=AC+ 3 CD E C A D B G F E D C B A B C D A P E A B C D E5 16. A B C D 17. EH=FH ED=FD DH EF _ 17 18 18. ABC AB=AC AB AB D AC E BCE 10 AB -BC=2 BC A 6 B 4 C 7 D 8 19. ABC DE GF
4、AC BC CD AD AD=8 BG =10 AB=_ 20. ABC AF BAC AC BC E B=70 F AE=19 C=_ D E F H A B C D E A B C D E F G A B C D E F6 21. P AOB PC OA PD OB C D CD OP CD 22. OP AOB PA OA A PB OB B A PA =PB B PO APB C AB OP D OA=OB 23. AOP= BOP PC OA PD OB PC PD _ OP AOB P O D C B A A B O P O B C D A P7 24. P AOB OM C D
5、OA E F OB PD OA PE OB A P C=PE B PC=PF C PD=PF D PD=PE 25. A B C A B C D 26. BD ABC DE AB E AB =6 BC=8 S ABC =14 DE=_ 27. ABC 21 BO CO ABC ACB OD BC D OD=3 ABC _ O C B A D P F E M C B A A B C D E A B C D O8 28. AD ABC DE AC E BF AC ED F BC ABF AE =2BF DE=DF DB =DC AD BC AC=3BF A 4 B 3 C 2 D 1 29. AB
6、 CD BP CP ABC DCB AD P AB AD=8 P BC A 8 B 6 C 4 D 2 30. AD ABC DF AB F DE=DG ADG AED 50 39 EDF A 11 B 5.5 C 7 D 3.5 31. BAC BC D DE AB DF AC E F AB =6 AC =3 BE=_ F E D C B A A B C P D G F E D C B A A B C D G E F9 32. ABC BAC BC PQ P P PN AB N PM AC M BN CM 33. ABC AC BC BC P PA+PC=BC A B C D Q P M N
7、 C B A A B C A B C P A B C P A B C P A B C P10 34. P l P PQ l P l A B A B 1 2 AB Q PQ PQ l _ 35. Rt ABC ABC =90 D BC B C BC BC P PD AC E BE ED BC A= EBA EB AED ED = 1 2 AB A B C D 36. A B l1 l 2 O AOB P A B l1 l2 P Q A B P l A B C D E P l 2 l 1 B O A11 37. A B C ABC C C C 38. ABC C =90 B =30 A AB AB AC M N M N 1 2 MN P AP BC D 1 D AB 2 ACD 1 ADB B A P N M D C B A