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在△ABC中,内角A,B,C的对边分别为a,b,c,a+b=5,(2a+b)•cosC+c•cosB=0. (1)若△ABC的面积为,求c; (2)若点D为线段AB的中点,∠ACD=30°,求a...
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△ABC的内角A.B.C.的对边分别为abc已知2cosCacosB+bcosA=c.Ⅰ求C.Ⅱ若c
设△ABC的内角ABC的对边长分别为abcb2=ac求B.
已知△ABC的内角A.BC的对边分别为abc若cosA-C+cosB=1a=2c则角C.=.
△ABC的内角A.B.C.的对边长分别为abc若则b=
△ABC的内角A.B.C.的对边分别为abc已知a=bcosC+csinB则B.=.
在△ABC中已知abc分别为△ABC内角ABC的对边.若b=a且sinB.+cosB.=0则A=.
△ABC的内角A.B.C.的对边分别为abc若abc成等差数列且2a=3c则cosB=
在锐角△ABC中内角A.B.C.的对边分别为abc且2asinB.=b.1求角A.的大小2若a=6b
.在△ABC中内角A.B.C.的对边分别为abc且c=2b=a则△ABC面积的最大值为.
△ABC的内角A.B.C.的对边分别为abc已知a=bcosC+csinB.1求B2若b=2求△AB
在锐角△ABC中内角A.B.C.的对边分别为abc且2asinB=b.求角A.的大小.
在△ABC中abc分别为内角A.B.C.的对边且2asinA=2b+csinB+2c+bsinC则A
△ABC的内角
,
,
的对边分别为a,b,c,若c=2,b=6,B.=120°,则a=( ) A. 6B. 4 C. 3
2
在△ABC中内角A.B.C.的对边分别为abc已知a-b=2c=4sinA=2sinB.则△ABC的
在△ABC中内角A.B.C.的对边长分别为abc且2b-ccosA.=acosC.1求角A.的大小2
设△ABC的内角A.B.C.的对边分别为abc且则c=___________
在锐角△ABC中内角A.B.C.的对边分别为abc且2asinB.=b.求角A.的大小.
△ABC内角ABC的对边分别为abc若则△ABC的面积S=.
△ABC的内角A.BC的对边分别为abc若2bcosB=acosC+ccosA则B.=
△ABC在内角A.B.C.的对边分别为abc已知a=bcosC+csinBⅠ求B.Ⅱ若b=2求△AB
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对任意的n∈N*不等式1+n≤ea恒成立其中e是自然对数的底数则实数a的最大值为
Asweallknowthewarisanancientcustomwhichhasexistedforatleastsixthousandyears.Itwasalwaysevilandusuallyfoolishbutinthepastthehumanracemanagedtolivewithit.Modernskillhaschangedthis.Eithermanwillstopwarorwarwillstopman.Forthepresentitisnuclearweaponsthatcausethegreatestdangerbutbacteriological细菌学的orchemicalweaponsmaybeforelongofferanevengreaterthreat.Isitpossibletopersuademankindtolivewithoutwar?Ifwesucceededinstoppingwartherewouldbenodangerforus.Todothisweneedtopersuademankindtolookuponinternationalquestionsinanewwaynotbycontestsofforceinwhichthevictorygoestothesidewhichismostskillfulinmassacre大屠杀butbyarbitration仲裁inaccordancewithagreedprinciplesoflaw.Itisnoteasytochangeoldmentalhabitsbutthisiswhatmustbeattempted. Therearethosewhosaythattheadoptionofthisorthatideology意识形态wouldpreventwar.Ibelievethistobeacompleteerror.Allideologiesarebaseduponbeliefswithoutproofwhichareatleastdoubtfulandatworsttotallyfalse.Thosepeoplewhobelievethemarewillingtogotowarinsupportofthem. Themovementofworldopinionduringthepasttwoyearshaschangedverylargelysuchaswecanwelcome.Ithasbecomeacommonbeliefthatnuclearwarmustbeavoided.Ofcourseverydifficultproblemsremainintheinternationalworldbutthespiritinwhichtheyarebeingapproachedisabetteronethanitwassomeyearsago.Ithasbeguntobethoughtevenbythepowerfulmenwhodecidewhetherweshallliveordiethatagreementsshouldbereachedevenifbothsidesdonotfindtheseagreementswhollysatisfactory.IthasbeguntobeunderstoodthattheimportantconflictnowadaysisnotbetweenEastandWestbutbetweenManandtheHi﹣techbomb. 1Whatcanwelearnfromthefirstparagraph? A.Wemayfacegreaterthreatfromweapons. B.Nuclearweaponsareworstofall. C.Man'sideaofvictoryhaschanged. D.Dangerousweaponsareforbiddennowadays. 2Theauthorofthepassagebelievethat. A.itisimpossibletolivewithoutwar B.differencesbetweenEastandWestwillleadtowar C.warwillbestoppedbymodernskill D.warmustbestoppedifmanwantstosurvive 3Whichistheonlywaytostopwaraccordingtotheauthor? A.Tostopnuclearweapons. B.Tosettleinternationalissuesthroughagreements. C.Todestroybacteriologicalandchemicalweapons. D.Toletthestrongersidetakeovertheworld. 4Wecaninferfromthelastparagraphthat. A.nuclearwarwilldefinitelynottakeplace B.realagreementshavebeenreachednow C.worldopinionisstilldividedonnuclearwar D.manisbeginningtorealizethatnuclearwaristhegreatestenemy 5Whatdoestheauthorfeelwhilewritingthispassage? A.Hopeful. B.Doubtful. C.Worried. D.Disappointed.
已知空间向量=1-10=3-21则||=
Itimpressedmealot.Ineverthoughtthatlittlehelpwould1outtobethemostsatisfyingthingIhaveeverdone.Hewastiredand2toclimbfurther.Withabroad3heaskedifIcouldhelphimwithsomemoney.Hewasparalyzedinbothlegsandwas4fundsforsomeoperation.Hesaidthatifoperatedsuccessfullyhecould5trainingguaranteeinghimajob.Iwasfullof6andevenaskedhimtoshowhislegs.Igavehimthe7money.Afterafewdaysheagaincameatmydoorstepaskingformoremoneyforaccommodation.ThistimeIwasmoreorless8heisnotcheatingme.IgavehimsomeandsaidthisisallIhad. AyearwentbyandIhadmovedtoan9place.OnefinedayIgotacallfromanunknownnumber.ThecallercalledouthisnamebutIdidn't10him.ThenhesaidheistheveryparalyzedpersonIhelpedayearago. Iaskedhimhowheisdoing.HesaidWhatsir?yourecognizemenotbymynamebutbymy11state. WithyourkindhelpIamnowableto12onmylegswithoutsupport.Iwasoperated13.Iammarriedtoabeautifulladyandhaveastable14. Idon't15rememberifIgavehimmyphonenumber.16whathesaidnextwastouching.HesaidhewantedtoreturnmymoneysothatIdidn'tfeelcheatedandcontinuedtohelppeople17inthefuture.Idon'tknowwhetherhereadmyfacialexpressionthedayIhelpedhimbuttearswere18downmyface.ThatdayIpromisedhimIwillcontinuetohelppeopleasIseean19﹣smallorbig.20thatchangedmylife. 1A.send B.bring C.turn D.break 2A.playing B.substituting C.struggling D.walking 3A.look B.whisper C.view D.smile 4A.raising B.finding C.seeking D.earning 5A.pretend B.attend C.intend D.tend 6A.doubts B.minds C.worries D.depression 7A.remaining B.left C.hiding D.forgotten 8A.informed B.outspoken C.convinced D.prepared 9A.bad B.old C.systematic D.new 10A.remind B.recognize C.replace D.repeat 11A.disabled B.messed C.excited D.stressed 12A.live B.stand C.focus D.base 13A.surprisingly B.successfully C.hopefully D.naturally 14A.reason B.promise C.character D.job 15A.also B.even C.already D.only 16A.Therefore B.Otherwise C.However D.Meanwhile 17A.infavor B.inplace C.inadvance D.inneed 18A.running B.putting C.bringing D.pulling 19A.behavior B.case C.accident D.opportunity 20A.Strangely B.Truly C.Generally D.Originally
已知函数fx=ln1+f1=ln2. Ⅰ证明f<x Ⅱ若[f2+f22+…+f2n]≤m对任意的n∈N*均成立求实数m的最小值.
复数z=1-2i则|z|=||=.
设x∈R则“2<x<3”是“|x-2|<1”的
函数fx=-lnx-2的零点个数为.
对任意的n∈N*不等式1+n≤ea恒成立其中e是自然对数的底数则实数a的最大值为
函数fx=-lnx-2的零点个数为.
Jennywasdrivinghersix﹣year﹣oldsonTonytohispianolesson.TheywerelateandJennywasbeginningtothinksheshouldhavegivenitup.TherewasalwayssomuchtodoandJennyrecentlyhelpedwithanoperation.Shewastired.Thestormandiceroadsaddedtohertension.Maybesheshouldturnthecararound. Mom!Tonycried.Look!Justaheadacarhadlostcontrolonthepatchofice.AsJennytappedthebrakestheothercarwildlyrolledoverthencrashedsidewaysintoatelephonepole. Jennypulledoverstoppedandthrewopenherdoor.Thankgoodnesssheknewherjobwell﹣shemightbeabletohelptheseunfortunatepassengers.Thenshepaused.WhataboutTony?Shecouldn'ttakehimwithher.Littleboysshouldn'tseesceneslikethat.Butwasitsafetoleavehimalone?Whatiftheircarwerehitfrombehind?ForabriefmomentJennyconsideredgoingonherway. SheaskedTonytostayinthecarandranslippingandslidingtowardthecrashsite.Itwasworsethanshe'sfeared.Twogirlsofhighschoolageinthecar.Onewaskilled.Thedriverhoweverwasstillbreathing.Jennyquicklyappliedpressuretothewoundintheteenager'sheadwhileherpracticedeyecheckedtheotherinjuries.Abrokenlegmaybetwoalongwithprobableinternalbleeding.Butifhelpcamesoonthegirlwouldlive. Atruckerhadpulledupandwascallingforhelponhiscellphone.Soonambulanceandrescueworkerscame.Goodjobonesaidwhileexaminingthewounds.Youprobablysavedherlife!LaterthefamiliesofthevictimscametomeetJennyexpressingtheirgratitudeforthehelpshehadoffered. 1WhatwasJennydoingwhentheaccidenthappened? A.Shewashelpingwithanoperation. B.Shewasdrivingforherson'slesson. C.Shewasdrivinghomewithherson. D.Shewasmakingatelephoneforhelp. 2WhatdoesJennydoaccordingtothepassage? A.Ataxi﹣driver. B.Afirefighter. C.Anurse. D.Ateacher. 3Thecaraccidentwascausedby. A.thetirednessofthedriver B.thetruckwhowastelephoningwhiledriving C.thestudents'carelessdriving D.thebadweatherandterribleroadconditions 4BeforegoingtorescuethewoundedJennyworriedalotabout. A.herpoorskillsofsavingpeople B.herlittleson'ssafetyinthecar C.herlittleson'spianolesson D.thestudentskilledintheaccident 5Wecaninferfromthepassagethat. A.thedriverwassavedthankstoJenny'stimelyhelp B.therewereatleasttwodeathsinthecaraccident C.Jennywastoblamefortheterriblecaraccident D.Jennywaslateforhispianolessonsforthisaccident
已知函数fx=ln1+f1=ln2. Ⅰ证明f<x Ⅱ若[f2+f22+…+f2n]≤m对任意的n∈N*均成立求实数m的最小值.
已知函数fx=x3+ax+4a∈R. Ⅰ若a=-4求函数fx的单调递增区间 Ⅱ若a≥-9且函数fx在区间[03]上单调递减求a的值.
若过点P1n可作两条不同直线与曲线y=x2+2x-1≤x≤2相切则n
Tinyastheyarebatshavetheabilitytoseeinthedarkbyusingaspecialskillcalledecholocation回声定位法.Theymakenoisesandwaitforsoundwavesoranechotobounce反弹backoffobjects.Theycantellthedistanceofvariousobjectsbyhowquicklythesoundwavesbouncebackoffthem.Ifnosoundbouncesbacktheycanthenflyforward. Thisspecialabilityhasbeensimulatedinthehumanworldforalongtimesuchasinsubmarinesandplaneswhosesonar声呐systemsaresomewhatsimilartoecholocation.Butapartfromhelpingvehiclesseewheretheyarewhatifblindpeoplecoulduseecholocationforthemselves?Itturnsoutsomealreadyare. AmericanDanielKishwhoisblindisknownasBatman.Thisisn'tbecausehewalksaroundinacape披风andamaskbutbecausehehasabat﹣likeabilitytolocatewhereheisthroughsharpclickshemakesbymovinghistongueagainsttheroofofhismouth.Kishissoskilledatecholocatingthathecanrideabikeandhikeonhisown. RecentlyresearchcarriedoutattheUniversityofDurhaminEnglandshed揭示somelightonthepowerofhumanecholocation. Kishworkedwithagroupofscientistswhostudiedthewayblindpeoplelistentotheechoesthattheyproducefromclicks. Theteamwhichconductedexperimentswithothervolunteersfoundthatpeoplewerecapableofhearingevenveryfaintechoesonesfarfainterthanhadbeenpreviouslythought. SpeakingtoTheIndependentLoreThalerleadscientistofthegroupsaidWefoundthatinsomeconditionstheywerereallyfaint﹣about95percentsofterthantheactualclicksbuttheecholocatorswerestillabletosensethis. AndrewKolarikoftheUniversityofCambridgeisanotherexpertinecholocation.ReactingtotheDurhamstudyhetoldBBCNewsthatecholocationcanbeveryusefulatprovidinginformationatfaceorchestheightandcouldhelppeopleavoidobjectslikelowhangingbranchesthatmightnotgetdetectedbythecane盲杖oraguidedog. AlthoughKish'sskillisremarkablethere'shopeforotherblindpeoplewhowanttouseecholocation.AccordingtoBBCNewsecholocationisaskillblindpeoplecanacquireanddevelopjustlikelearningalanguage.AsKolariksaidTeachingecholocationskillscouldprovideblindpeoplewiththemeansofexploringnewplaces. 1TheunderlinedwordsimulatedinParagraph2probablymeans. A.copied B.discovered C.improved D.challenged 2HowdoesKishlocatewhereheis? A.Byusinghisgreatsenseofhearing B.Bylisteningtotheechoesproducedbyhiscane. C.Viathesonarsystemattachedtohisbody. D.Viatheechoesfromtheclickshemakeswithhistongue. 3WhatdidLoreThaler'steamfindfromtheirstudies? A.Itishardforecholocatorstosensefaintechoes. B.Humanscanecholocatebetterthanwethoughtwecould. C.Echolocatorscanpickupalltypesofechoes. D.Blindpeoplearebetterecholocatorsthanthosewhocansee. 4Accordingtothearticleteachingecholocationtoblindpeople. A.isnoteasytoputintopractice B.willenablethemtogetridoftheircane C.willopenupnewpossibilitiesforthem D.willimprovetheirabilitytolearnanewlanguage 5Whatisthearticlemainlyabout? A.Differenttypesofhumanecholocation. B.Theimportanceofhumanecholocation. C.Studiesonblindpeopleusingecholocation. D.Whybats'echolocationcouldbeusedbyhumans.
已知空间向量=1-10=3-21则||=
已知函数fx=x3+ax+4a∈R. Ⅰ若a=-4求函数fx的单调递增区间 Ⅱ若a≥-9且函数fx在区间[03]上单调递减求a的值.
Whereareyougoingtocollege?I'mgoingtomylocalcommunitycollege.Myanswerseemedtobethemagicphrasethatwouldwipethesmilerightoffmanypeople'sfaces.It'sclearthatpeoplehavealotofmisconceptions误解aboutcommunitycolleges. Manypeoplethinkcommunitycollegesareonlyforpeoplewhocouldn'tgetintoafour﹣yearschool.Butitisnottrue.InhighschoolIalwaysgotA's.ButwhenitcametoapplyingtocollegesIhadnoideawhatIwantedtomajorinandcouldn'tjustifyspendingthousandsofdollarsata4﹣yearschooluntilIknewwhatIwantedtodo.Myparentswereverysupportiveofmydecisiontoattendthecommunitycollege. SomepeoplewillaskSincethecommunitycollegeischeaperwillyougetagoodeducation?Ifoundthatnearlyallofmyprofessorstaughtthesamecoursesat4﹣yearcolleges.MyprofessorswereknowledgeableandexperiencedandIfoundmanyofthecourseschallenging. SomepeoplethinkifIattendthecommunitycollegeIwillmissoutonthecollegeexperience.ImustadmitthatthisissomethingIworriedaboutagreatdealthesummerbeforecollege.ButIsoonlearnedthatthecommunitycollegejustlikeanyothercollegeiswhatyoumakeofit.Istrivedtomakethemostofmytimeatthecommunitycollege.Ialsomadetonsoffriendsbyjoiningclubsandattendingstudentgovernmentmeetings. Itookalotofdifferentcourses.IhadanamazingprofessorwhosuggestedItakeherjournalismclass.NeverhavingwrittenformyhighschoolnewspapersIdarednottakeitbutsinceshewassoenthusiasticIeventuallydecidedtohaveatry.ThatonecoursewasallittookformetorealizethatIwantedtobecomeajournalist. IlookforwardtograduatingthisMaytopursueacareerinbroadcastjournalism.Communitycollegesmaynotbeforeveryonebutformeitisalife﹣changingexperiencethathashelpedmediscoverwhoIamandthepersonIhopetobecome. 1Whatwastheauthor'sparents'attitudetowardshis/herdecisionaboutattendingthecommunitycollege?nomorethan5words 2WhatdoestheunderlinedpartmissoutoninParagraph4mean?1word 3Howdidtheauthormakefriendsatcommunitycollege?nomorethan12words 4Whydaren'ttheauthortakethejournalismclassatfirst?nomorethan12words 5Inyouropinionwhatkindofeffectdoesattendingthecommunitycollegehaveontheauthor?nomorethan15words
已知函数fx=x4+ax3+2x2+b其中ab∈R.若fx仅在x=0处有极值则a的取值范围是若a=4则fx的所有极值点之和为.
已知椭圆=1a>b>0的左右焦点分别为F1F2焦距为4若以原点为圆心F1F2为直径的圆恰好与椭圆有两个公共点则此椭圆方程为
若过点P1n可作两条不同直线与曲线y=x2+2x-1≤x≤2相切则n
已知函数fx=x4+ax3+2x2+b其中ab∈R.若fx仅在x=0处有极值则a的取值范围是若a=4则fx的所有极值点之和为.
假设你应邀参加学校组织的英语学习师生座谈会请你根据下表所提示的信息用英语写一篇发言稿简单介绍自己英语学习的情况并对学校今后的英语教学提出建议. 注意 1对所给要点逐一陈述适当发挥不要简单翻译. 2词数150左右.开头和结尾已经写好不计人总词数. DearteacherandschoolmatesIt'sagreatpleasureformetobetodayandsharemyexperienceoflearningEnglishwithyou. Thankyouforlistening.
已知椭圆=1a>b>0的左右焦点分别为F1F2焦距为4若以原点为圆心F1F2为直径的圆恰好与椭圆有两个公共点则此椭圆方程为
复数z=1-2i则|z|=||=.
设mn是两条不同的直线αβ是两个不同的平面有下列四个命题其中正确的是
设x∈R则“2<x<3”是“|x-2|<1”的
己知等比数列{an}{bn}的公比分别为pqp≠qn∈N*. Ⅰ若a1=b1=1p=2q=4求数列{}的前n项和Sn Ⅱ若数列{cn}满足cn=an+bn求证数列{cn}不是等比数列.
己知等比数列{an}{bn}的公比分别为pqp≠qn∈N*. Ⅰ若a1=b1=1p=2q=4求数列{}的前n项和Sn Ⅱ若数列{cn}满足cn=an+bn求证数列{cn}不是等比数列.
已知圆Ox2+y2=4直线2x﹣y+b=0与圆O相切则b的值为
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