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在△ABC中,角A,B,C所对的边分别为a,b,c,bsinB+csinC=a(+sinA) (1)求A的大小; (2)若a=,B=,求△ABC的面积
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高三下学期数学《》真题及答案
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在△ABC中已知角
,
,
所对的边分别为a,b,c,且a=3,c=8,B.=60°,则△ABC的周长是( ) A.17,B.19,C.16,
18
三角形ABC中角A.BC所对的边分别为abc已知求边C.及面积S.
在△ABC中角ABC所对应的边分别为abc若a=csinA则的最大值为.
在△ABC中角A.B.C.所对的边分别为abc设向量p=a+cbq=b-ac-a若p∥q求角C.的大
已知在△ABC中角A.B.C.所对的边分别为1求△ABC中的最大角2求角C.的正弦值
在△ABC中角A.B.C.所对的边分别为abc.若A.B.C.构成等差数列那么角B.等于.
在△ABC中角A.B.C.所对的边分别为abc已知1求角A.的大小2若a+b=4c=3求△ABC的面
在△ABC中角ABC所对的边分别为abc如果a=2c=A=30°那么△ABC的面积等于.
在△ABC中已知角ABC所对的边分别为abc.若asinA.-sinB.=csinC.-bsinB.
在△ABC中角A.B.C.所对的边分别为abc设S.为△ABC的面积满足则角C.的大小为
.△ABC中角A.B.C.所对的边分别为abca=5b=7B.=60°则c=__________.
在周长为16的三角形ABC中AB=6AB所对的边分别为ab则abcosC的取值范围是.
在△ABC中角A.B.C.所对的边分别为abc若abc成等比数列则角B.的取值范围为.
.在△ABC中角A.B.C.所对的边分别为abc且b2+c2=a2+bc则角A.的大小为.
在△ABC中abc分别为角A.B.C.所对的边若a=2bcosC则此三角形一定是________三角
在△ABC中角A.B.C.所对的边分别为abc若
在△ABC中角A.B.C.所对的边分别为abc且b2+c2=a2+bc则角A.的大小为
在锐角△ABC中abc分别为角A.B.C.所对的边且a=2csinA.角C.=________.
在△ABC中角A.B.C.所对的边分别为abc若a=1∠B=450△ABC的面积s=2.1求边b的长
在锐角△ABC中abc分别为角A.B.C.所对的边且a=2csinA则角C.=________.
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图中能正确表示基因分离定律实质的是
Althoughtheideaofzeroemissionnetcarbon﹣positivesustainable可持续developmentwaspromotedworldwidemostcitiesareatalosswhattodoorevensomehaveobjectedtoit.ButinLiuzhouacityinsouthernChinaattitudescouldnotbemoredifferent. TheLiuzhouMunicipalityUrbanPlanningBureauhassignedupItalianarchitectStefanoBoerithefatheroftheforestcitymovementtobuildaself﹣containedcommunityforupto30000people.Heisthego﹣tomanforsuchprojectsthankstothesuccessofhisverticalforeststworesidential住宅的towers.Completedin2014theyremoveupto17.5tonsofsoot煤烟fromtheaireachyearandayearlateroneofthemwasnamedBestTallBuildingWorldwide. TheLiuzhouprojectisamuchmoreambitiousundertakinghowever.Itshomeshospitalshotelsschoolsandofficeswillbebuiltona340﹣acresiteinwhatBoericallsthefirstattempttocreateanurbanenvironmentthatisreallytryingtofindabalancewithnature.Its100speciesofplantlifeareexpectedtoabsorbalmost10000tonsofcarbondioxideand57tonsofpollutantsperyearwhileatthesametimeproducing900tonsoflife﹣givingoxygen. Althoughthearchitectshaven'tpublishedthecostoftheforestcitytheMilantowerscostonlyfivepercentmorethantraditionalskyscrapers. TheconstructionofhisforestcityatLiuzhouissettobeginin2020andthereisstillagreatdealofplanningandresearchrequiredbeforeaprojectedcompletiondatecanbeset.HoweverBoeriremainsoptimisticabouttheprojectandhasconfidenceinthesoundnessofhisvisionIreallythinkthatbringingforestsintothecityisawaytodealwithglobalwarming. 1What'sLiuzhou'sattitudetowardsthesustainabledevelopment? A.Approving. B.Cautious. C.Unfavorable. D.Doubtful. 2WhyisStefanoemployedfortheLiuZhouproject? A.Hevolunteeredtodotheproject. B.Heisafamousarchitectintheworld. C.Heisthefatheroftheforestrecovery. D.Hehasgainedexperienceinsimilarprojects. 3Whatdoestheunderlinedwordtheyreferto? A.Thearchitects. B.Thetwotowers. C.Forestsinthecity. D.Theresidentsofthecity. 4What'sthepurposeofLiuZhouproject? A.Toprovidemorejobs. B.Tobringforestintocity. C.Tosolvehouseshortage. D.Toimprovetheenvironment.
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实验室常用的电流表和电压表都由电流计G其实就是小量程的电流表改装而成的.电流计G也是有电阻的同样遵从欧姆定律.现有一个满偏电流量程为3.0mA内阻为Rg=1Ω的电流计G.小明同学利用所学的物理知识将该电流计G改装成了一个既可以测量电流也可以测量电压的多用电表其电路原理如图所示.当接AB两个接线柱时可以当作量程是0.6A的电流表使用当接AC两个接线柱时可以当作量程为3V的电压表使用求电阻R1R2的阻值大小结果保留三位小数.
小明家电能表上月底的示数和本月底的示数如图所示他家本月消耗的电能为kW•h他家同时使用的用电器总功率不得超过W.
Asafirstresponderyouneverknowwhattypeofsituationyoumightwalkintoorwhoyou'llmeetalongtheway.That'sdefinitelybeenthecaseforJeffreyLanenberga51﹣year﹣oldparamedic急救医务人员since1984. TenyearsintothejobLanenbergreceivedacallthatreportedthatamaninhisearly30shadfallendownintheMallofAmerica.WhenLanenbergandhispartnerarrivedatthescenetheyfoundtheyoungmalefacedownontheground.Hehadgoneunconsciousmakingweakattemptstobreathe.Hiswifestoodbesidehimholdingtheirsmallsoninhorror.Theyquicklyrushedtodefibrillate除颤andcalmthemantokeephimundercontrol.AfterLanenbergdroppedthepatientoffattheneighboringhospitalhethoughtaboutthemanandhisfamilyforalongtime. LanenbergthoughthehadexperiencedeverythingunderthesununtilonerandomvisittoOfficeMaxthreeyearsagowherehemetamanrepeatedlywalkbackandforthwhilestaringathim.Asitturnedoutthemanwasthepatienthehadsaved20yearsearlier. Yougaveme20yearsmorethanIeverthoughtI'dhavethemansaid.HethankedLanenbergrepeatedlyandtoldhimhehadsomeonehewantedhimtomeet.Hesteppedaroundthecornerandreappearedwitha20﹣something﹣year﹣oldman.Lanenberginstantlyknewthatitwasthesonhehadseenstandingbyhismotherallthoseyearsago. ThatdaychangedmylifeLanenbergsaid.Beforethateverythingwasaboutwork…WhenItalktomybeginner﹣trainingclassItellthemyouneverknowtheimpactyoucanhaveonsomeone'slife. 1WhatdidLanenbergdowiththeyoungman? A.Hegavethemanthefirstaid. B.Hecuredthemanatthescene. C.Heonlysentthemantohospital. D.Hetookcareoftheman'swifeandson. 2WhatdidLanenbergthinkoftheencounterwiththeman? A.Itwasunbelievable. B.Itwasacommonroutine. C.Itwasamatterofcourse. D.Itwasadangeroussituation. 3WhywasthemanthankfultoLanenberg? A.Lanenberghelpedbringuphislittleson. B.Lanenbergdonatedtosupporthisfamily. C.Lanenberggavehimthepresenthappylife. D.Lanenbergtaughthissontobeanewdoctor. 4HowdidthemeetingchangeLanenberg'slife? A.Hechangedhisattitudetohisjob. B.Hewasrewardedwithmuchmoney. C.Hegotapromotiontobeateamleader. D.Hetookupteachingworktotrainnewcomers.
LastweekVodafonestartedatestoftheUK'sfirstfull5GserviceavailableforusebybusinessesinSalford.ItispartofitsplantotrialthetechnologyinsevenUKcities.Butwhatcanweexpectfromthenextgenerationofmobiletechnology? Onethingwewillseeinthepreparationforthetestislotsoftrickswiththenewtech.Earlierthisyearoperatorspaidalmost£1.4billionforthe5Gwavelengthsandtocompensateforthatcashtheywillneedtocatchtheeyeofconsumers.InSeptemberVodafoneuseditsbitoftherangetodisplaytheUK'sfirsthologram全息call.TheManchesterCitycaptainStephHoughtonappearedasaholograminNewbury.Itisn'tallhologramshowever5Gwillofferfasterinternetaccess.withOfcom英国通讯管理局suggestingthatvideothattakesaminutetodownloadon4Gwillbeavailableinjustasecond. Thewiderapplicationistosupportconnectedequipmentontheinternetofthings﹣notjusttheinternet﹣enabledfridgethatcanreorderyourmilkforyoubutthenetworkthatwillenabledriverlesscarsanddeliverydrones无人机tocommunicatewitheachother. ProfWilliamWebbhaswarnedthatthetechnologycouldbeacaseoftheemperor'snewclothes.Muchofthespeedincreaseheclaimscouldhavebeenachievedbyputtingmoremoneyinthe4Gnetworkratherthananewtechnology.OtherdifferentvoiceshavesuggestedthatafocusonrollingoutwiderruralbroadbandaccessandaddressingcurrentnetworkcoveragewouldbemorebeneficialtotheUKasawhole. Obviously5Gwillalsobringacosttoconsumers.Itrequiresahandsetforboth5Gand4Gandthefirst5G﹣enabledsmartphonesareexpectedinthecomingyear.Withtheslowpaceofnetworkrolloutsofaritislikelythatconsumerswillendupupgradingtoanew5Gphonewellbefore5Gbecomeswidelyavailableinthenextcoupleofyears. 1WhydoesProfWilliamWebbsaythetechnologycouldbeacaseoftheemperor'snewclothes? A.Heisinfavoroftheapplicationofthenewtechnology. B.5Gwillbringacosttoconsumersintheirdailylife. C.5Ghelpspeoplecommunicatebetterwitheachother. D.Heprefersmoremoneytobespenton4Gnetworks. 2Theunderlinedwordaddressinginthefourthparagraphhastheclosestmeaningto. A.makingaspeechto B.tryingtosolve C.managingtodecrease D.respondingto 3Thelastparagraphindicatesthat. A.it'lltakeseveralyearstomake5GaccessibletothepublicintheUK B.5Gserviceshowshugedevelopmentpotentialandabroadmarket C.customersareeagertouse5Gsmartphonesinsteadof4Gones D.it'sprobablethat5GnetworkrolloutisspeedingupinBritain 4Whatdoweknowaboutthetext? A.Vodafoneissuccessfulinspreadingthe5Gservice. B.StephHoughtonappearedasahologramby4G. C.Theapplicationof5Gwillmakelifemucheasier. D.5GphonesareavailableinruralareasoftheUK.
如图所示的电路中电源电压保持不变R2=20Ω闭合开关S移动滑动变阻器R2的滑片到中点c时电流表的示数为0.4A移动滑片P到最左端a时电流表的示数为0.3A求电源电压和R1的阻值.
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Thereareseveraldifferenttypesoffiredepartments.Somehirefull﹣timepaidfirefightersandsomearerunentirelybyvolunteers.1afirefightermustgothroughstrictphysicalandacademictrainingtoensureastrongknowledgeoffiresafetyandthephysicalstrengthtohandlethetasksrequiredbymembersofafiredepartment. Joiningafiredepartmentrequiresthatbothphysicalandwrittentestsarepassedwithscoresshowingathoroughknowledgeoffiresafety.2. Thefirststepinjoiningafiredepartmentasapaidfirefighteristosubmitanapplicationaswellasacquiretheappropriatetraining.Usuallyfirefightersmusthaveahighschooldiplomaandsomecompletetwo﹣or﹣four﹣yearprogramsinfirescienceatcommunitycollegesanduniversities.3andifacandidatealreadyhasconnectionsatafiredepartmenthemayapplyforapositionstraightoutofhighschool. Onceacandidateappliesandisacceptedfortrainingatafiredepartmenthemustthencompleteseveralweeksoftrainingatthedepartment'strainingcenter.4.Whenthisisdonethecandidateissenttoafirecompanyforaperiodofprobation实习.Hehastocontinuetraininginthenewpositionwhilebeingdirectedbyexperiencedfirefighters.5.Anapplicationmustbesubmittedtothevolunteerfiredepartmenttheniftheapplicationisacceptedthecandidatewilllakeatrainingprogramandthenberequiredtopassaphysicalandwrittentest.Firefightersmustalsobecomecertified认证asEmergencyMedicalTechniciansEMTs.ThelevelofEMTcertificationisdeterminedbytheindividualdepartments. A.Althoughitisdemanding B.Whichevertypeisdesired C.Howeveranacademicprogramisnotrequired D.Forvolunteerfirefighterstheprocedureissimilar E.Butjoiningavolunteerfiredepartmentistotallydifferent F.Trainingconsistsofclassroomworkandpracticaltraining G.Alsoacandidatemustbeabletorespondquicklyinemergencies
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小华探究凸透镜的成像规律. 1课间小华到室外利用太阳光来测量凸透镜的焦距她将该凸透镜正对着太阳光如图甲所示.此时纸上呈现一个并非最小的光斑时测得这个光斑到凸透镜的距离为L.此时再将这个凸透镜与纸之间距离稍微增大若光斑变大则凸透镜的焦距fL选填“>”“<”或“=”调整以后得到该透镜的焦距为10cm. 2当烛焰位于如图乙所示位置时移动光屏可在光屏上得到一个清晰的像此成像规律常用在选填“放大镜”“照相机”或“幻灯机”上保持凸透镜位置不变将点燃的蜡烛放在光具座上20cm刻线处要在光屏上重新得到烛焰清晰的像应将光屏向选填“左”或“右”移动. 3当烛焰再次位于如图乙所示位置时若将蜡烛稍远离凸透镜光屏上的像变模糊若不移动光屏要再次在光屏上得到清晰的像则可在蜡烛和凸透镜之间再放上一个焦距合适的选填“近视眼镜”或“远视眼镜”.
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FromAntiguatoZanzibarfthesespotspromiseanincredibletripfor2019. AntiguaGuatemala Antiguaiswortheverypennybutthatdoesn'tmeanyou'llhavetoemptyyourwalletsaysHudson.Thereareplentyofbudgel﹣carisciousactivities.Itwon'tcostyouacointovisitSantoDomingodelCerroanoutdoorsculpturepark.Wantingsomethingsweet?HeadtoChocoMuseo.Admissionisfreeandsoarethesamples! OdessaUkraine Odessaishavingabitofatourismboomnationwide﹣notthatwe'resurprisedgivenitssandybeachesandpastel﹣coloredbuildings﹣butit'sstillfairlyundertheorderforinternationalaudiences.Youcanalsocountonthisportcityforaffordablefun.TicketstotheOdessaOperaHousestartatamere﹩2! BogotaColombia TravelersonbudgetwillfindColombia'svastcapital.farmoreofabargainandeverybitasfascinatingsaysHudson.It'sfreetovisitMuseodeOroandonSundaysmanyofthebigroadsareclosedtoaccommodatefoodcartsstreetentertainersandpedestrians. Zanzibar Zanzibarattractsvacationerswithitswhitesandbeachesgreenish﹣blueddescolorfulcoralreefsandoceanfrontseaside.OfcoursewanderinginhistoricStoneTownisprettyappealingtoo.Eitherwayyouneedn'tspendapennyinthisamazingplace.It'salsoworthnotingthatJozaniForestistheonlyplaceintheworldyoucan9eeendangeredredcolobusmonkeys. 1Whichofthefollowingrequiresadmissionfee? A.ChocoMuseo. B.StoneTown. C.MuseodeOro. D.OdessaOperHouse. 2WhatisspecialtoZanzibar? A.Whitesandbeaches. B.Colorfulcoralreefs. C.Redcolobusmonkeys. D.HistoricStoneTown. 3Whatdothefourdestinationshaveincommon? A.Theyarecoastalcities. B.Theyareinexpensivetovisit. C.Theywelcomestreetentertainers. D.Theywillmakeyourwalletempty.
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Balletisaformalkindofdanceperformancewitharichandinterestinghistory.ThewordballetcomesfromtheFrenchlanguageand1bebasedontheItalianwordballetto.Ballettomeansalittledance.Ballet'searlyrootsbeganinItalyinthelate1400s.ButitwasinFrance2balletdevelopedintotheformweknowtoday. TheFrenchrulerLouistheFourteenthhadabiginfluence3thedirectionofballetinitsearlyhistory.HeruledFranceforseventy﹣twoyears4startin1643.Hestarteddancingasaboyandworkedharddaily. LouistheFourteenthturnedballetintoaformofdancethatreflected5hepowerandinfluence.Ballet'smanyrulesand6extremedetailedmovementsexpressedaperson'spowerandsocialrelations.Thekingmadesurethatballetbecamea7requireforthepeopleofhiscourt.HealsostartedtheRoyalAcademyofDance8importantpeoplecouldlearnthisart.Theaimofthisdancewasself﹣controlorderandperfection. Balletslowlychangedfromadanceattheking'scourttoone9performbyprofessionaldancers.WhenLouistheFourteenthdiedin1715ballet10bringtoodierpartsofEuropeandwasdevelopinginotherways.
面镜不是使光线透过而是使光反射回去的仪器光线遵循反射定律如图甲是凹面镜它将平行主轴的入射的光线会聚在焦点F上这是因为表面每个点的法线方向不同光线以不同的角度反射根据光路可逆性凹面镜不仅可以使平行光线汇聚于焦点还能使过焦点的光线反射成平行于主轴的光请根据以上叙述在图乙中画出H0的成像光路图.
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