小学奥数-几何五大模型(鸟头模型)

模型二鸟头模型△ABC中，DABD在E在AC则SACAE)△ABC△ADEDAADEEBCBC如图在△ABC中，DAD:AB2:5，AE:AC4:7，S△ABC16△ADEAADDEEBCBC，SAD:AB2:5(24)，△ADE△ABESAE:AC4:7(45)S(25)S8△ABE△ABC△ADE△ABC△ADE则S35S16123570△ABC的△ABC△ADE70．ABC是的5AC是的3ABC1/8AADEDEBCBC【解析】．ECAE∵∴S3SVABCVABEABAD∴515S15S15．SVADESSVABEVABCVABCVADEBDDC4，BE3，AE6AAEE乙乙甲甲BCBCDD【解析】∵．3，3BEBEAE6∴，3SABSVVBDEABDBDDC4，∴2S6S，S5S．SSVABCVABDVABCVBDE乙甲】△ABC在D在EABAD:5:2，ACAE:EC3:2，S△ADE12△ABCDDAAEEBCBC【解析】，:ADAB:2:5(23):(53)SS△ADE△ABES:SAE:AC3:(32)(35):(32)5，△ABE△ABCS:S(32):5(32)6:25625S12SS△ABC△ADE△ABC△ADE△ADE122550△ABC50】E为AFCF8DCFABE【解析】223的2362/88648．】△DEF7,2,3△ABCAFDBCE:(BDBEBABC):()1):(23)1:6，SSSS△BDE△CEF△ADF△ABC:S:S(CECF):(CBCA)3):(24)3:8(ADAF):(ABAC)(21):(34)1:6△ABC△ABC设244份，S4份，S9份，S2444977SS△ABC△BDE△ADF△CEF△DEFS24△ABC】ABC3AB:BE2:5，BC:CD3:2BBEAEACCDD【解析】2BC3BE5BD325:(ABBCBEBD)(23):(55)6:25):(SS△ABC△BDES6310.525250.512.5△ABC形的面积是12.51313】(ABCD6，BC．ADEB【解析】CF11323、3:SCFCE):CBAC)12:(33)2:9S66218S4；S△CEFS△ABC△ABC△CEF:S2:3S183212，S6△CDE△ACD△CDE△CDF故SSSS412610△DEF△CEF△DEC△DFC】ABC1至DCA至FAF3ACBC至ECE2BC3/8FFAEECCBDD【解析】法1．、CD1S∵，1，SVABCS1VABCVDBC∴S1．VDBC18．法2VABC和VCFEACB与FCEBC111SSAC∴．VABCFCCE42818．VFCE又SSVABCVFCE6，SS3．VADFVBDE186318．SSSSSVDEFVABCVFCEVADFVBDE】，，2CBGDDC4，3，ABCD的ABCDCF2，ABCDEFGHHHBBEAEGCGCDFF【解析】、AC△ABC和BFEABC与BC111SAB∴．△ABCSBEBF13313．△FBE又SS△ABC△FBES8，S△DHG15，S8．S△GCF△AEHSSSSS8815+3+236．EFGH△AEH△CFG△DHG△BEFABCD21S．ABCDEFGHS3618】EFGH66CBBFDCCGDAABCDHHCGCGDDBBAAFFEE4/8【解析】:(CDCBCGCF):()1:2S2SSS△BCD△CGF△CGF△CDB:1:2S2SSS△ABD△AHE△AHE△AHES△ABDSS2(S)2S△CGF△CBD△ADB四边形ABCDSS2SAC△DHG△BEF四边形ABCDSSSSSS5S四边形EFGH△AHE△CGF△HDG△BEF四边形ABCD四边形ABCDS66513.2四边形ABCD】ABCD、、、、、、EFGHCBCDABCD．EFGHFFBABACDEECGGDHH【解析】、AC．，22BC4SS4S．SBFSBEFABCHDGADCBEFAE4S4S4S．SHDG，ABAHABCADCABCD33ADS9SS9S．AEHABDCFGCBD9S9S9S．SSSAEHCFGABDCBDABCDSSSSS4S9SS12S60．EFGHBEFHDGAEHCFGABCDABCDABCDABCDABCD1】△ABC至DBC至E，F是AC的2△ABC2△DEFAFCBED【解析】△ABC和CFEACB与FCEBC224SSAC∴．△ABCFCCE1112S0.5．VFCE△FCE又SVABC2，3．SS△ADF△BDES20.5323.5SSSS△DEF△ABC△CEF△DEB△ADF】S1，BC5BD，AC4EC，DGGSSE，AFFGS．△ABCVFGSAFECGSBD【解析】5/83．432111．SS△FGS5432210△FGS】ABG8是是F是GABCDECEEEADADFFGGCCBB【解析】、EG．1816S△BCFS△CDE248，8SSVAEFVEFGS16，S32，VBFCABFE24S12SVABFVABG】四个面积为1HAFEBGCD【解析】AGF与CEHAGF与CEH4aa421761．6643FA4a，FBa．77BDC、AEC，所以ABC12的131349491313ABC6496．49ABCDE．EADBC【解析】CDBC6/8AE1111213