第第頁(yè)共16頁(yè)J/sJ.DN-tt)=2t-6解：過(guò)盅E柞EN丄胡于N,這按MG如郅（由題可得：zBEN=50a.BD=l?t=trCE=2J/sJ.DN-tt)=2t-6解：過(guò)盅E柞EN丄胡于N,這按MG如郅（由題可得：zBEN=50a.BD=l?t=trCE=2Ct-3}=2t-6.,,BE=6-(21-5]-12-21FBN=BE-cosB=1BE=6-tr\DN=EC.八DEM是等邊三歯形r;.DE=EM,wDEM=￡『?.^NDE+zNED^O"rzhlED+zMEC^lSO0-30°-60°=^,,\zNDE=2MEC*在-DNE和-EC何中”DN=EC、￡NDE=^CEM<DE=EMl-DNEmaECM,.^DNE^ECM=9Dar?.M勰動(dòng)的苗徑丸過(guò)熬亜直于B匸餉，當(dāng)1好時(shí)rE在點(diǎn)B,D在AE的中點(diǎn),jttBjCM=EN^CD^B匚嘩區(qū)令石:當(dāng)時(shí)，E在扁C,D在為Ar此時(shí)康N1癥怎匚.時(shí).M點(diǎn)殛歷的踣徑氏為320—2、解:fe-ABC中pzACB=90°?AC=JJBCN,AB=5.sinA=iFtan&=2”如圖■當(dāng)CD.AB時(shí)「MCD為直聞三龜戰(zhàn)，.\CD=AC*sinA=12t■-ad=y.jc--cd2二l?處NDtEwABC,ASfit血CDE中.DE二CDHanzD匸E二芋技半二弓raEE=AB-AD-DE=5-2?皀二工21-1、解；當(dāng)工DE価獲三ft腳毎可MUCDW以AawBmDCE.CED沁B弋DCE;MWzCED=J<CDE.又?NB弋DCEF^CDE=zBD<,.\zB匚匚ED訂「aBD=BC=4丄21-2、9-5.-.RpaCH中.AH=，'在R1」CDH中FCO2=CH￡+DH2=(11)2+〔9-h)2=)(2?55交注CDEnEDJ^dce=^br,\-BOC"-CDEr?W2=DE-DBr?W2=DE-DBr21-3、-W解：當(dāng)直建I與言銭尸嚴(yán)*電平行時(shí)r設(shè)直^的解析式為y=T直線I經(jīng)過(guò)敝10),0②如團(tuán)1中「作CEl0A,.ianzOAC=0②如團(tuán)1中「作CEl0A,.ianzOAC=OC$_,OA=Tj.zOAC=30°f,-^ace=wr22-2、：=解：①對(duì)王醉廠也電F-^x=O^y=g,令y=0得JC=-1F解:①如圉2中，當(dāng)a=15WrTCEllOD,nODHFfvzOAC=新fr^ACD=zADC=15fl,.'.AD=A匚=AB(tADRF丄ADC是等匿三角形，tOD垂直平倉(cāng)BC「aDB=DCr"D眈是擁三用胳；②當(dāng)at二殆CT時(shí)f?3?zDAC=zDCA=3O^..\DA=DC=DB,/>ABDhiACD.iBCD均為密S三鶴形；③當(dāng)ot三105°時(shí),ASD=zADB=zADC=z