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曲线C的极坐标方程为C：ρ2＝，直线的参数方程为（t为参数） （1）写出C的直角坐标方程与l的普通方程； （2）直线l与曲线C相交于两点A，B，设点M（0，﹣1），求的值．
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高三下学期数学《》真题及答案
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已知在直角坐标系xOy中直线l的参数方程为t为参数以坐标原点为极点x轴的正半轴为极轴建立极坐标系曲线
在平面直角坐标系中直线l的参数方程为t为参数在以直角坐标系的原点O.为极点x轴的正半轴为极轴的极坐标
在直线坐标系xoy中曲线C.1的参数方程为t为参数a＞0在以坐标原点为极点x轴正半轴为极轴的极坐标系
在平面直角坐标系xOy中直线m的参数方程为t为参数在以O.为极点射线Ox为极轴的极坐标系中曲线C.的
已知曲线C.的参数方程为α为参数直线l的参数方程为t为参数以坐标原点为极点x轴的正半轴为极轴建立极坐
选修4—4坐标系与参数方程 在直线坐标系xOy中曲线C1的参数方程为t为参数a＞0在以坐标原点为极
在直线坐标系xOy中曲线C1的参数方程为t为参数a>0.在以坐标原点为极点x轴正半轴为极轴的极坐标系
已知曲线C.的极坐标方程是ρ=2sinθ设直线l的参数方程是t为参数.1将曲线C.的极坐标方程转化为
在直角坐标系xOy中直线l的参数方程为t为参数在以O.为极点x轴的非负半轴为极轴建立的极坐标系中曲线
已知直线l的参数方程为t为参数0≤φ＜π以坐标原点O.为极点x轴的正半轴为极轴建立极坐标系曲线C.的
已知在平面直角坐标系xOy中以坐标原点O.为极点以x轴正半轴为极轴建立极坐标系曲线C1的极坐标方程为
在直角坐标系xOy中过点P.21的直线l的参数方程为t为参数以坐标原点为极点x轴正半轴为极轴建立极坐
选修4—4坐标系与参数方程 在直线坐标系xOy中曲线C1的参数方程为t为参数a＞0在以坐标原点为极
在平面直角坐标中以坐标原点为极点x轴的正半轴为极轴建立极坐标系已知曲线C.的极坐标方程为直线l的参数
在直线坐标系xoy中曲线C.1的参数方程为t为参数a＞0在以坐标原点为极点x轴正半轴为极轴的极坐标系
在平面直角坐标系中以坐标原点为极点x轴的非负半轴为极轴建立极坐标系.已知曲线C.的极坐标方程为ρ=4
已知曲线C.1的参数方程为t为参数以坐标原点为极点x轴的正半轴为极轴建立极坐标系曲线C.2的极坐标方
已知曲线C.的参数方程为t为参数以坐标原点为极点x轴的正半轴为极轴建立极坐标系则曲线C.的极坐标方程
选修4—4坐标系与参数方程.已知曲线C.的极坐标方程为直线的参数方程为t为参数0≤＜.Ⅰ把曲线C.的
已知曲线C.的极坐标方程是ρ=6cosθ以极点为平面直角坐标系的原点极轴为x轴的正半轴建立平面直角坐
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集合A＝{x∈N|log2x+1＜2}B＝{x|x≤2}则A∩B的子集个数为
已知数列{an}满足对任意的正整数nk都有an+k+an﹣k＝2ann＞k且该数列前三项依次为又已知数列{bn}的前n项和为Sn且b1＝1bn+1＝Snn≥1 1求{an}{bn}的通项公式 2令cn＝anbn求数列{cn}的前n项和Tn．
已知双曲线a＞0b＞0的左右焦点分别为F1F2点P在双曲线上若|PF1|+|PF2|＝6a且△PF1F2最小内角的大小为30°则双曲线C的渐近线方程为
15分FormorethansixmillionAmericanchildrencominghomeafterschoolmeans1cometoanemptyhouse.SomedealwiththesituationbywatchingTV.Somemayhangoutoutside.2allofthemhavesomethingincommon.Theyspendpartofeachdayalone.They3calllatchkeychildren﹣theyarechildrenwholookafterthemselveswhiletheirparentswork.Andtheirbadsituationhasbecomeasubjectofconcern. Aheadmasterofanelementaryschoolsaidthattherewasaschoolruleagainstwearingjewelry.Alotofkidshadchainsaroundtheirneckswithkeys4attach.Hewasconstantlytellingthemtoputtheminsideshirts.Thereweresomanykeysallof5werehousekeys. Hebegantalkingtothechildrenwhohadthem.Thenhelearnedtheinfluencethatworkingcouplesandsingleparentswerehaving6theirchildren.Fearisthebiggestproblemfacedbychildrenathomealone.Manyhadnightmaresandwereworriedabouttheirown7safe. Themostcommonwaylatchkeychildrendealwiththisisbyhiding.Itmightbeinabathroomunderabed8inacloset.ThesecondisTV.They'llwatchitwiththevolumeturneduphigh.Mostparentsdon'trealize9iteffectontheirchildrenandmostparentsareslowtoadmitthefact10theyleavetheirchildrenalone.
已知三棱锥P﹣ABC的四个顶点都在半径为3的球面上AB⊥AC则该三棱锥体积的最大值是
15分假如你是李华最近刚到美国一所大学求学在学习生活上遇到了问题想向导师Mr.Brown求助.请你写封邮件内容包括 1.问题描述2.请求帮助3.预约时间. 注意1.词数80左右2.可以适当增加细节以使行文连贯.
25分阅读下面短文根据其内容写一篇60词左右的内容概要. FormostofussocialmedialikeTwitterandFacebookisapartofoureverydaylives﹣atworkhomeorboth.Butalotofpeoplearestillfiguringoutwhentouseitandhow.Thisisespeciallytrueinhighschoolwheremanyteachersareunsureofhowitfitsintheclassroom. DanKrutkaahighschoolteacherisanadvocateforusingsocialmediaintheclassroomandisanenthusiasticuserofTwitterhimself.Krutkasaysit'sagreatwaytocommunicatewithhisstudentsduringnonclasshours.YoucancontinuetolearntogetheroutsidetheclassroomsaysKrutka.SowhenstudentsarepostingonTwitter﹣saytheypostsomethinginaccuratelyortheymakeareallygoodpoint﹣Icangoaheadandrespondtothembeforeclass. Krutkasaystweetingwithhisstudentsisn'tjustaboutconvenienceit'salesson.Hesaysstudentsneedtolearnhowtousesocialmediaproperly.Peopleusesocialmediairresponsiblyandschoolshouldbeaplacewherewe'retalkingaboutthatandhowtouseitresponsiblyhesays.AsateacherIthinkpartofmyjobistohelpstudentsunderstandhowtomakebestuseofitasthoughtfullearners. ButKrutkaisamongthefeweducatorswhofeelthisway.ManyschoolsincludingthoseinWesternMassachusettsarestillstrugglingwithwhetherornotTwitterorFacebookshouldbeusedasteachingtools.Manyteachersbelievethatsocialmediaingeneralcaneasilydistractstudents.SeanKavanaghaninthgradeworldhistoryteachertriedusingTwitterinclassbutwasdistractedbyallofthenonclassrelatednoise. Besidesitseemsthatsomestudentsdon'tfeellikethiswayeither.RayLynnisinKavanagh'shistoryclass.I'dratherkeepmyschoolandmypersonalsocialmedialifealittlemoreseparateshesays.I'drathernothavemyteacheronmyTwitterorFacebook.
己知xy满足则x﹣2y的最大值为
回答下列与生态系统相关的问题． 1在森林生态系统中生产者的能量来自于生产者的能量可以直接流向答出2点即可． 2通常对于一个水生生态系统来说可根据水体中含氧量的变化计算出生态系统中浮游植物的总初级生产量生产者所制造的有机物总量．若要测定某一水生生态系统中浮游植物的总初级生产量可在该水生生态系统中的某一水深处取水样将水样分成三等份一份直接测定O2含量A另两份分别装入不透光甲和透光乙的两个玻璃瓶中密闭后放回取样处若干小时后测定甲瓶中的O2含量B和乙瓶中的O2含量C．据此回答下列问题． 在甲乙瓶中生产者呼吸作用相同且瓶中只有生产者的条件下本实验中C与A的差值表示这段时间内C与B的差值表示这段时间内A与B的差值表示这段时间内．
7.5分IntheU.S.stateofWashingtonaroadcalled^Interstate90^cutsthroughawildmountainousareatoreachthecityofSeattle.Forthearea'smanykindsofanimalsthebusyhighwaygreatlylimitstheirmovements.Crossing1﹣90﹣astheroadiscalled﹣isariskybutsometimesnecessaryact.Butsoonanimalswillhaveasaferchoiceforcrossingtheroad.Theywillbeabletogoaboveit. Tohelptheanimalsthestateisfinishingworkonitslargest﹣everwildlifebridge.The11﹣meter﹣tall20﹣meter﹣widestructurebeginsintheforest.Itformstwoarchesabovethehighwayoneforeachdirectionoftraffic.Workersareaddingfencingandplantstohelpguidetheanimalsacrossthebridge.Two﹣meter﹣thickwallswillhelpblocknoisefromvehiclesbelow. The1﹣90BridgeispartofagrowingnumberofwildlifecrossingsacrosstheUnitedStates.Somearefencessomeareoverlandbridgesandsomeareunderpasses.Theyallaimtokeepdriversandanimalsawayfromeachother.Collisionsbetweenanimalsanddriversarerarelydeadlytopeople.Buttheyareoftendeadlytowildlife.InCanada'sBanffNationalParkstudieshavefoundthatwildlifecrossingsreducethearea'sanimal﹣drivercollisionsby80percent. Mostofthewildlifebridgesareinwesternstates.Butexpertshavenotedmanyotherareasthathaveaneedforsuchpaths.JenWatkinswhoseorganizationhashelpedcampaignforanimalcrossingssaysftindformorecrossingsisthenumber﹣onebarrier. PattyGarvey﹣DardaoftheU.S.ForestServicehasworkedonthe1﹣90crossingfromthestartoftheproject.Shesaysthe﹩6﹣millionbridgewillonedaypayforitselfbecausethehighwaywillnothavetobefullyorpartlyclosedeachtimealargeanimalisstruck.ShesaidIfyoushutdownInterstate90youshutdowninterstatecommerce. 1WhatisthepurposeofbuildingthebridgeoverInterstate90? A.Toreducehumandeathsincrashwithwildlife. B.Topreventwildlifefrombeingstruckbyvehicles. C.Toarousepublicawarenessofwildlifeprotection. D.Toprovideasaferchoicetocrosstheriskyroad﹣ 2AccordingtoJenWatkinswhatisthebiggestchallengeincrossingconstruction? A.Findingwaystohelpguideanimalsacrossthebridge. B.Collectingmoneytobuildmorewildlifecrossings. C.Locatingareastoconstructappropriatecrossings. D.Encouragedriverstoobeytheregulationsoftraffic. 3WhatdotheunderlinedwordsinParagraph5imply? A.Thebridgewillprovetobewellworththehighprice. B.Expenseforbuildingsuchbridgeswillbereduced. C.Thebridgewillgreatlypromotetradeandcommerce. D.Livessavedthroughthebridgearedefinitelybeyondprice.
30分Cruz11andAnthony10couldn'tagreewerethebirdsoutontheiceducksorgeese?Therewasonlyonewaytofindout.Soona1Januaryeveninglastyearthetwofriends2ontothefrozenpondneartheirhomesinFrankfortIllinoistogeta3look.Firsttheythrewarockontotheiceto4itthentheysteppedonit.5theicewouldholdtheirweightAnthonytookafewstepsthen…FOOMP.Hecrashed6theseeminglyfrozensurface.TherewasnosoundnocrackhesaidIjustfellthrough7. Cruzrushedtohelphis8friend.FOOMP﹣thepond9himtoo.Theboyswereuptotheirnecksinicywaterandquicklylosing10intheirlimbs.Anychanceoftheirfreeingthemselveswas11.Cruzwassurehewasgoingtodie.Anthony'ssisterhadseenitandstartedscreamingforhelp. JohnLavinaneighbor12nearbyheardherandquicklypulledover.Seeingtheboyshegrabbedanearbybuoy救生圈withonehandkickedoffhis13andranintotheicywaterhittinghiswaythroughtheicewithhisfree14.EventuallyLavin15hiswaytoCruzandAnthonyandpulledthembacktoland.Theyweretakentothe16wheredoctorsdiscoveredthattheirfive﹣minutestayinthewaterhad17theirbodytemperaturenearlytendegrees. 18theboyshavefullyrecoveredthankstotheir19neighbor.JusttothinksaysCruz20hewasn'tthereIcouldhavedied. 1A.warm B.chilly C.rainy D.windy 2A.toured B.rushed C.ventured D.wandered 3A.casual B.actual C.better D.deeper 4A.test B.break C.hit D.see 5A.Bothered B.Persuaded C.Concerned D.Convinced 6A.through B.onto C.in D.across 7A.slowly B.apparently C.instantly D.gradually 8A.discouraged B.panicked C.frustrated D.confused 9A.drowned B.drew C.embraced D.swallowed 10A.balance B.feeling C.faith D.heart 11A.givingaway B.slippingaway C.slippingout D.givingout 12A.driving B.passing C.coming D.walking 13A.bags B.gloves C.shoes D.clothes 14A.fist B.leg C.arm D.finger 15A.felt B.broke C.swam D.made 16A.shelter B.home C.school D.hospital 17A.lowered B.raised C.lessened D.changed 18A.Unexpectedly B.Fortunately C.Naturally D.Immediately 19A.strong B.considerate C.fearless D.friendly 20A.unless B.until C.when D.if
7.5分The13thofJune1325IleftTangiermybirthplacewiththeintentionofmakingthepilgrimagetoMecca去麦加朝圣…toleaveallmyfriendstoabandonmyhomeasbirdsabandontheirnests.SobeginsanoldmanuscriptinalibraryinParis﹣thetraveldiaryofIbnBattuta. AlmosttwocenturiesbeforeColumbusthisyoungMoroccansetoffforMeccareturninghomethreedecadeslaterasoneofhistory'sgreattravelers.DrivenbycuriosityhejourneyedtoremotecornersoftheIslamicworldtravelingthrough44moderncountriesthreetimesasfarasMarcoPolo.LittlecelebratedintheWesthisnameiswellknownamongArabs.InhishometownofTangierasquareahotelacafeaferryboatandevenahamburgerarenamedafterhim. IbnBattutastayedinMeccaasastudentforseveralyearsbuttheurgetotravelsoontookover.InoneadventurehetraveledtoIndiaseekingprofitableemploymentwiththesultan﹣theMuslimrulerofDelhi.Onthewayhedescribedhisgroupbeingattackedintheopencountryby80menonfootandtwohorsemen…IwashitbyanarrowandmyhorsebyanotherbutGodinhisgracepreservedme…InDelhithesultangavehimthepositionofjudgebasedonhispreviousstudyatMecca.ButthesultanhadanunpredictablecharacterandIbnBattutalookedforanopportunitytoleave.WhenthesultanofferedtofinanceatriptoChinaheagreed.IbnBattutasetoffinthreeshipsbutmisfortunestruckwhilehewasstillontheshore.Asuddenstormgroundedandbrokeuptwoshipsscattering散播treasureanddrowningmanypeopleandhorses.Ashewatchedthethirdshipwithallhisbelongingsandslaves﹣onecarryinghischild﹣wascarriedouttoseaandneverheardfromagain. AfteralifetimeofamazingadventuresIbnBattutawasfinallyorderedbytheSultanofMoroccotoreturnhometosharehiswisdomwiththeworld.Fortunatelyheagreedandwroteabookthathasbeentranslatedintonumerouslanguagesallowingpeopleeverywheretoreadabouthisunparalleledjourneys. 1WhatcanwelearnaboutIbnBattutafromthepassage? A.HehadgreatinterestintheIslamicworld. B.Hereturnedtohishomelandtowriteabook. C.HisjourneyswerelessimportantthanMarcoPolo's. D.Hisjourneyswereverycommonforpeopleofthattime. 2TheSultanofDelhigaveIbnBattutaapositionofjudgebecause. A.IbnBattutahadstudiedinMecca B.IbnBattutahadbeenajudgebefore C.IbnBattutahadbeenpopularwithArabs D.IbnBattutahadtraveledtomanycountries 3Whichisthebesttitleforthepassage? A.TheLearnedIbnBattuta B.AVisitortoMecca C.TheTravelsofIbnBattuta D.DesireforAdventures
物质W是一种含氮有机物会污染土壤．W在培养基中达到一定量时培养基表现为不透明．某研究小组欲从土壤中筛选出能降解W的细菌目标菌．回答下列问题． 1要从土壤中分离目标菌所用选择培养基中的氮源应该是． 2在从土壤中分离目标菌的过程中发现培养基上甲乙两种细菌都能生长并形成菌落如图所示．如果要得到目标菌应该选择菌落进一步纯化．选择的依据是． 3土壤中的某些微生物可以利用空气中的氮气作为氮源若要设计实验进一步确定甲乙菌能否利用空气中的氮气作为氮源请简要写出实验思路预期结果和结论即． 4该小组将人工合成的一段DNA转入大肠杆菌使大肠杆菌产生能降解W的酶酶E．为了比较酶E与天然酶降解W能力的差异该小组拟进行如下实验请完善相关内容． ①在含有一定浓度W的固体培养基上A处滴加含有酶E的缓冲液B处滴加含有相同浓度天然酶的缓冲液C处滴加三处滴加量相同． ②一段时间后测量透明圈的直径．若C处没有出现透明圈说明若AB处形成的透明圈直径大小相近说明．
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