(名师整理)最新数学中考二轮复习《圆》专题冲刺精?含答? - 百度文库 ر

MAPաCBPSAS PMPC ߡPCM60

MPCΪȱΣ PCCM CA+CBPC

PPDABOB ߡPABǵȱΣ PDԲOBPD30㣬 BDAB2

RtBDPУDP6

RtBDOУݹɶã6OB2

+22OB2

OB4

PCΪԲֱʱCA+CBֵΪ8 ʴΪ8

⣺BDCFK

ABCDEFΣ

- 25 -

18

BAFAFE120㣬FAFE FAE30㣬

BAE90㣬֤ͬAEDBDE90㣬 FGCKaAFBCAB2a CF4aAE2AG2a

ʴΪ

19⣺ߡBCA90㣬BAC30㣬 AB2BC8AC

BC4

RtABCA˳ʱת90õRtADE CAEBAD90㣬

BCɨӰSBADSCAE

4У ʴΪ4У

20⣺

ԲΪOOOECDEOD

ͼֲ6ԲABҴСȵСԲCDУAB66Բİ뾶Ϊ6 OEOD

3

- 26 -

RtOEDУɹɶãDEOECDOEO DECE

CD

ʴΪ

⣨10С⣩

211֤DEΪOߣ ODDE DEBC ODBC ODAC OAOD AODA AC BABC

2⣺BDͼBExBCBA5 ABΪֱ

ADBBDC90㣬 ߡDBECBD BDEסBCD

BDBCBEBDBDEC BD2

BC?BE5x

RtBDEУBD2

DE2

+BE2

5x22

+x2

x11

x24ȥ

- 27 -

BE1 tanBDE

tanC

22֤1ͼOD

ACΪOߣABΪOֱCAB90㣽ADB ODOB DBOBDO COBD

AOCOBDCODODB AOCCODAOODCOCOAOCաDOCSAS CAOCDO90㣬 ODCDODǰ뾶 CDǡOߣ

2O뾶ΪrODOBr

- 28 -