1、 2015 24. AB O B O BM / CD BM AB F DA DC AC AD AD BM E (1) ACD (2) OE 2 DE OE 2014 21 AB O C AB O BD AC D E OB CE DB F AF O H BH 1 AC=CD 2 OB=2 BH A B C D E F M O 2013 20 AB O PA PC O A C PC AB D DE PO PO E 1 EPD= EDO 2 PC=6 tan PDA= OE & *# 2012 20 1 2 AB O C O OD BC D C O OD E BE BE O AD BE F 9 OB
2、 2 sin 3 ABC BF 2011 20. ABC AB O AC BC D E F AC 1 BF O 2 BC BF 2010 20 ABC D AB O D B C DOC ACD 1 AC O 2 ACB O 2 BD . AB AC 1 2 CBF CAB 5 AB 5 sin 5 CBF D E F A O C B 2009 20. ABC AB=AC,AE BM ABC AE M, B,M O BC G, AB F,FB O . 1 AE O 2 BC=4,cosC= O . 2008 19 1 2 1 3 Rt ABC 90 C O AB O OA AC AB DE CB
3、D A BD O : 8:5 AD AO 2 BC BD DCOABE 2015 2014 21. 5 1 CO BD O AB ABD = 90 C AB COA = 90 CO BD O AB C AD AC = CD 2 CO AB E OB OB =2 OE = 1 = BE CO FD COE FBE BF = CO = 2 AB AHB = 90 = ABF BFH = AFB ABF BHF BH FH BF = 1 2 BF = 2 BH = = 2013 20 AB O PA PC O A C PC AB D DE PO PO E 1 EPD= EDO 2 PC=6 tan
4、PDA= OE & *# 2012 20. 1 OC . EC O C . 90 . . . . ECO OB OC OCB OBC OD DC DB DC OE BC . . . . 90 . EB EC ECB EBC ECO EBO EBO AB O . BE O . 2 D DM AB M DM FB . Rt ODB 2 90 9 sin 3 sin 6.ODB OB ABC OD OB ABC 22 3 5. BD OB OD Rt DMB 22 sin 2 5. 5. DM BD ABC BM BD DM O AB 18. 13. AB AM AB BM DM FB . . 36
5、 5 . 13 AMD ABF MD AM BF AB MD AB BF AM 2011 20 AE. AB O AEB=90 . 1+ 2=90 . AB=AC F E C B M A O D A O B C D E F G 1 2 1= 2 1 CAB. CBF= 2 1 CAB 1= CBF. CBF+ 2=90 . ABF=90 . AB O BF O . C CG AB G. sin CBF= 5 5 1= CBF sin 1= 5 5 . AEB=90 AB=5. BE=AB sin 1= 5. AB=AC AEB=90 BC=2BE= 5 2 . Rt ABE 5 2 2 2 B
6、E AB AE . sin 2= 5 5 2 cos 2= 5 5 . Rt CBG GC=4 GB=2. AG=3. GC BF AGC ABF. AB AG BF GC . 3 20 AG AB GC BF . 2010 2009 20 1 2 OM OM OB 12 BM ABC 13 23 OM BC AMO AEB ABC AB AC AE AE BC 90 AEB 90 AMO OM AE AE O ABC AB AC AE 1 2 BE BC ABC C 1 4 cos 3 BC C 1 1 cos 3 BE ABC ABE 90 AEB 6 cos BE AB ABC O r
7、6 AO r OM BC AOM ABE O B G E C M A F 1 2 3 2008 19 5 1 BD O 1 1 OD OA OD A ADO 90 C 90 CBD CDB CBD A 90 ADO CDB 90 ODB BD O 2 2 1 DE AE O 90 ADE : 8:5 AD AO 4 cos 5 AD A AE 3 90 C CBD A 4 cos 5 BC CBD BD 4 2 BC 5 2 BD 5 2 O OH AD H 1 2 AH DH AD : 8:5 AD AO 4 cos 5 AH A AO 3 90 C CBD A 4 cos 5 BC CBD BD 4 OM AO BE AB 6 26 rr 3 2 r O 3 2 DCOABE 1 DCOABH 2 2 BC 5 2 BD 5
