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在△ABC中,角A,B,C所对的边分别为,b,c,若△ABC的面积为bccosA,则cosB+sinC的最大值为
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高一下学期数学《》真题及答案
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在△ABC中角A.B.C.所对的边分别为abc.若asinBcosC+csinBcosA=b且a>b
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已知cosC+cosA﹣sinAcosB=0.1求角B
在△ABC中三边abc所对的角分别为
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2
+b
2
=
ab+c
2
,则角C.为( ) A.30°B.45°C.150°
135°
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
【发现问题】如图①在△ABC中分别以ABAC为斜边向△ABC的形外作等腰直角三角形直角的顶点分别为D
在△ABC中角A.B.C.所对的边分别为abC.若b-ccosA=acosC则cosA=
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
设△ABC的内角
, B,C.所对的边分别为a, b, c, 若
, 则 △ABC的形状为( ) A.直角三角形
锐角三角形
钝角三角形
不确定
在△ABC中已知角ABC所对的边分别为abc.若asinA.-sinB.=csinC.-bsinB.
△ABC的内角A.B.C.所对的边分别为abc.若a+b-ca+b+c=ab则角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若b-ccosA=acosC则cosA=_______
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若a=1∠B=450△ABC的面积s=2.1求边b的长
在△ABC中角A.B.C.所对的边分别为abc若满足a=4A.=30°的三角形的个数恰好为一个则b的
在锐角三角形ABC中内角A.B.C.所对的边分别为abc若b=2B.=且csinA.=acosC.则
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1Youprobablythinkyouwillneverbeatopstudent.Thisisnotnecessarilysohowever.Anyonecanbecomeabetterstudentifheorshewantsto.Here'show Planyourtimecarefully.Whenplanningyourworkyoushouldmakealistofthingsthatyouhavetodo.Aftermakingthislistyoushouldmakeascheduleofyourtime.Firstyourtimeforeatingsleepingdressingetc.Thendecideagoodregulartimeforstudying.2Aweeklyschedulemaynotsolveallyourproblemsbutitwillforceyourealizewhatishappeningtoyourtime. Findagoodplacetostudy.Lookaroundthehouseforagoodstudyarea.Keepthisspacewhichmaybeadeskorsimplyacornerofyourroomfreeofeverythingbutstudymaterials.Nogamesradiosortelevision.Whenyousitdowntostudyconcentrateonthesubject. Makegooduseofyourtimeinclass.3Listeningcarefullyinclassmeanslessworklater.Takingnoteswillhelpyourememberwhattheteachersays. Studyregularly.Whenyougethomefromschoolgooveryournotesreviewtheimportantpointsthatyourteacherisgoingtodiscussthenextdayreadthatmaterial.4Ifyoudothesethingsregularlythematerialwillbecomemoremeaningfulandyou'llrememberitlonger. Developagoodattitudetowardstests.Thepurposeofatestistoshowwhatyouhavelearnedaboutasubject.Theyhelpyourememberyournewknowledge.Theworldwon'tendifyoudon'tpassatestsodon'tbeoverworried. 5Youwillprobablydiscoverthemafteryouhavetriedthese. A.Thereareothermethodsthatmighthelpyouwithyourstudying. B.Don'tforgettosetasideenoughtimeforentertainment. C.Takeadvantageofclasstimetolistentoeverythingtheteachersays. D.Noonecanbecomeatopstudentunlessheorsheworkshard. E.Maybeyouareanaveragestudent. F.Makefulluseofclasstimetotakenotesofwhattheteachersaysinclass. G.Thiswillhelpyouunderstandthenextclass.
Eatricebrew酒酿inclass?Youmustbejoking.Butthat'swhathappenedinHefeiHupoMiddleSchoolinAnhui.Junior2studentstheremadetheirownricebrewtolearnaboutfermentation发酵. Thestudentshavealreadylearnedthelessoninclass.Buttheywon'treallyunderstandituntiltheymaketheirownbrewsaidLiangWentheirbiologyteacher. Studentsmadethebrewingroups.Theyfirstboughtyeast酵母andcookedtherice.Thentheymixedthericeandyeastcarefullytogetherinabigcleanbowl.Themostimportantthingistoputthebowlinawarmplace.Yeastworksbestthere.That'sthesecretofagoodricebrew!Afteraboutaweekthericebecomesricebrew. Ourbrewlookssodelicious.Icouldn'twaittotasteit!saidXiYiwena14﹣year﹣oldgirl.ButXihadtowaitbecausetheyhadtoeatitatthetastingparty.Duringthepartytheteacherheatedupeachgroup'sricebrewforeveryonetotaste.Thestudentsthenchoseonegroupasthebestbrewmaker. Somegroup'sbrewwaspopularandsooneatenupbutsomewassourandtastedterrible!Somestudentsevenboughtnewbrewbecausetheyfailedtomaketheirown. Workingtogetherbroughtushappinessnomatterwhattheresultwas!saidWangYajuna=15﹣year﹣oldgirl.Hergroupwasthebestintheclass. 1Putthefollowingstepsinthecorrectorder a.thericebecomesricebrew b.buyyeast c.putthebowlinawarmplace d.cooktherice e.mixtheyeastandricecarefullyinacleanhowl A.a﹣b﹣c﹣d﹣e B.b﹣a﹣c﹣d﹣e C.b﹣d﹣e﹣c﹣a D.b﹣d﹣a﹣e﹣c 2Theteacheraskedthestudentstomakebrewbythemselvesbecause. A.theteacherlikedtoeatricebrew B.theteacherwantedthestudentstofindoutaboutfermentationthemselves C.theteacherwantedtomakethestudentsworkharder D.theteacherwantedtofindoutwhomakesthebestbrew 3Somestudentshadsourbrewprobablybecause. A.theydidn'tgetthebestyeast B.theywantedtobuybrewfromsupermarkets C.theydidn'tputthebowlintherightplace D.theydidn'tcookenoughrice 4Thebesttitleforthispassageis. A.Afunlessonaboutfermentation B.Howtomakericebrew C.Thehappinessofworkingtogether D.Scienceoffermentation
计算﹣12019+×sin60°﹣﹣3.
下列说法正确的是
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Ihavealwaysthoughtofmyselfasadoer.InworkIcertainlywasandcontinuetobe.AsamomI'mmostlyadoer.Howevermy1forbreastcancermademe2Ihadn'tbeenadoerinthewayIwantedtobe﹣butthatwasaboutto3. SinceIbecamea4andreportedmanyplanecrashesI'vebeen5offlying.Myfamilyhad6beentoanothercontinenttogether.Nowthatthechemo化疗7asagifttomyselfmykidsandmymomItookthemalltoLondonto8lifebeforebeginningradiationeveryweekdayforsixweeks. ThistimeImadea9nottothinktoomuchaboutit.Lookinginthemirrorwithouthairyoudoyourbestto10yourdayasthoughitwereaday11youdiscoveredyourlump肿瘤.Theneverythingseemsdoable.12Ijustbookedthetrip.InLondoneverydayI13adifferentadventurefromwhichmyfamilyandIlearnedmuchand14ourselves. Ihadwantedtotakea15likethisforyearsbutlifeandworkhadgottenintheway.Now16lifeandworkwehadfinallydone17.Ihavethoroughlyenjoyedfamilylearning18livingbutnothingisbetterthanknowingthatmykidsfeel19forthetrip.Onedayperhapsthey'llrealizethatsometimesthebest20comesaftersurvivingyourgreatestfears. 1A.treatment B.reason C.concern D.anxiety 2A.ignore B.imagine C.realize D.doubt 3A.happen B.continue C.change D.arise 4A.pilot B.doctor C.tourist D.journalist 5A.tired B.fond C.afraid D.proud 6A.frequently B.already C.never D.just 7A.failed B.ended C.delayed D.approached 8A.save B.create C.celebrate D.improve 9A.wish B.decision C.judgment D.conclusion 10A.lookfor B.getridof C.lookbackon D.getthrough 11A.after B.before C.until D.when 12A.But B.So C.Otherwise D.Even 13A.expected B.planned C.experienced D.described 14A.enjoyed B.taught C.introduced D.trained 15A.rest B.lesson C.risk D.trip 16A.intermsof B.owingto C.regardlessof D.inadditionto 17A.them B.it C.everything D.something 18A.for B.by C.with D.beyond 19A.grateful B.eager C.ready D.sorry 20A.work B.chances C.love D.adventures
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分解因式x2+2x+1=.
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﹣2的绝对值为
Chinahasannouncedit'sabolishingitsone﹣childpolicy.Whatdifferencehasitmadestatisticallyspeaking? 400millionbirthsprevented Theone﹣childpolicyofficiallyinplacesince1979hasprevented400millionbirths.Parentshavefacedfinesandotherpunishmentsforhavingmorechildren. ThemajorityofthedecreaseinChina'sfertilityratehappenedinthe1970s.Itdroppedfrom5.8childrenperwomanin1970to2.7in1978.Despitetheone﹣childpolicytheratehadonlyfallento1.7by2013. 2128﹣babydeathsrate Sincetheone﹣childpolicywasintroducedbabygirlshavebecomemorelikelytodiethanboys. Inthe1970saccordingtotheUnitedNations60malesper1000livebirthsdiedundertheageofone.Forgirlsthefigurewas53.Inthe1980saftertheone﹣childpolicybecameofficialtherateforbothwas36.Bythe1990s26malesper1000livebirthsdiedbeforetheageofone﹣and33girls.The2000ssaw21boysper1000livebirthsdyingand28girls. 1.16boysbornforeverygirl SexuallyselectiveabortionshavebeenconsideredasamajorcauseofChina'sunusualimbalance. Gietel﹣BastenassociateprofessorinsocialpolicyatOxfordUniversitysaysthebirthsofmanygirlsarenotregisteredifparentshavebrokentherulebyhavingtwochildrenaddingofficialsoftenturnablindeye.It'sestimatedtherearenow33millionmorementhanwomeninChina. 421families WiththeageingofChina'spopulationandthecontinuationoftheone﹣childpolicya421homeisthedescriptiongiventohouseholdsinwhichtherearefourgrandparentcaredforbytwoworkingageparentswhothemselveshaveonechild. By2050it'spredictedthataquarterofChina'spopulationwillbe65orolder.Thepredicteddeclineinthenumberofpeopleofworkingageisthoughttohavepersuadedthegovernmenttodroptheone﹣childpolicy. 1Whenwasthebabydeathsrateforbothboysandgirlsequal? A.Inthe1970s. B.Inthe1980s. C.Inthe1990s. D.Inthe2000s 2Whatmakestheone﹣childpolicyabolishedaccordingtothepassage? A.Thedeclineofbirthrate. B.Theriseofbabydeathsrate. C.Thechangeoffamilystructure. D.Thedeclineofworkingagepeople. 3Thepassagesumsuptheonechildpolicyby. A.number B.example C.contrast D.analysis
Mostanimalsonlandareknowntousbutmanylivingthingsunderwaterarenot.Nowlet'sgettoknowsomeofthem. Seacucumber Seacucumberarestrangeanimalslivingatthebottomofthesea.Theywearbrownorpalegreencoatswithmanysticksup.Whensummercomestheystaydeeptosleepbecausetheyareafraidofheat.Andwhenitisautumntheymovetoshallow浅的waterandgettheirfood. Pike Thepikeisakindoffreshwaterfish.Theyaregoodswimmersandlikeswimmingnearboatswaitingtobefed.Theyhavesharpteethtocatchfishes.Whentheyareyoungtheyliveingroups.Howeverwhentheygrowuptheyprefertolivealone. Cuttlefish Acuttlefishcanswimquitefastsoitisalsocalledrocket火箭fish.Ithaseightarmsandtwofeelersonitsheadjustarounditsmouth.Itejectsink喷墨whenitisindanger.Itsmeatisdeliciousanditisoftenthefirstchoiceformanypeople. Octopus Anoctopushaslongarmswithwhichtocatchfoodandprotectitself.Whenitissleepingoneortwoofitsarmsarestillondutykeepingmoving.Onceitfeelssomethingdangerousitcanwakeupatoncetotakeaction. 1Seacucumbersstaydeeptosleepinsummerbecausethey. A.areafraidofhightemperature B.wanttogetstrongandfat C.areafraidoftheirenemy D.wanttolivealone 2Accordingtothepassagelikestoswimnearboats. A.theseacucumber B.thepike C.thecuttlefish D.theoctopus 3Whathappensifacuttlefishmeetsitsenemy? A.Itrushesattheenemyatonce. B.Itcutsoffoneofitsarms. C.Itbiteswithitssharpteeth. D.Itejectsinktotheenemy. 4Theofanoctopuscanhelpprotectitwhenindanger. A.color B.arms C.sound D.smells
YouprobablyknowwhoMarieCuriewasbutyoumaynothaveheardofRachelCarson.Oftheoutstandingladieslistedbelowwhodoyouthinkwasthemostimportantwomanofthepast100years? JaneAddams1860﹣1935 AnyonewhohaseverbeenhelpedbyasocialworkerhasJaneAddamstothank.Addamshelpedthepoorandworkedforpeace.Sheencouragedasenseofcommunity社区bycreatingsheltersandpromotingeducationandservicesforpeopleinneedIn1931AddamsbecamethefirstAmericanwomantowintheNobelPeacePrize. RachelCarson1907﹣1964 Ifitweren'tforRachelCarsontheenvironmentalmovementmightnotexisttoday.Herpopular1962bookSilentSpringraisedawarenessofthedangersofpollutionandtheharmfuleffectsofchemicalsonhumansandontheworld'slakesandoceans. SandraDayO'Connor1930﹣present WhenSandraDayO'ConnorfinishedthirdinherclassatStanfordLawSchoolin1952shecouldnotfindworkatalawfirmbecauseshewasawoman.ShebecameanArizonastatesenator参议员andin1981thefirstwomantojointheU.S.SupremeCourt.O'Connorgavethedecidingvoteinmanyimportantcasesduringher24yearsonthetopcourt. RosaParks1913﹣2005 OnDecember11955inMontgomeryAlabamaRasaParkswouldnotgiveupherseatonabustoapassenger.HersimpleactlandedParksinprison.ButitalsosetofftheMontgomerybusboycott.Itlastedformorethanayearandkickedoffthecivil﹣rightsmovement.TheonlytiredIwaswastiredofgivinginsaidParks. 1WhatisJaneAddamswell﹣﹣knownforinhistory? A.Hereffortstowinaprize. B.Herlackofpropertraininginlaw. C.Hersocialwork. D.Hercommunitybackground. 2WhatisthereasonforO'Connor'sbeingrefusedbythelawfirm? A.Herlackofpropertraininginlaw. B.Herlittleworkexperienceincourt. C.Thediscriminationagainstwomen. D.Thepoorfinancialconditions. 3Whomadeagreatcontributiontothecivil﹣rightsmovementintheUS? A.JaneAddams. B.RosaParks C.SandraDay D.RachelCarson. 4Whatcanweinferaboutthewomenmentionedinthetext? A.Theyarehighlyeducated. B.Theyaretrulycreative. C.Theyarepeace﹣lovers. D.Theyarepioneers.
已知∠AOB=60°OC是∠AOB的平分线点D为OC上一点过D作直线DE⊥OA垂足为点E且直线DE交OB于点F如图所示.若DE=2则DF=.
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