Passage13
Henrywasanofficeworkerinabigcity.Heworkedveryhardandenjoyedtravelinginhisholidays.
Heusuallywenttotheseaside,butoneyearhesawanadvertisementinanewspaper.“Enjoycountrylife.SpendafewweeksatWestHillFarm.Goodfood.Freshair.Horseriding.Walking.Fishing.Cheapandinteresting.”
“Thissoundsagoodidea,”hethought.“I’llspendamonthatWestHillFarm.IthinkIcanenjoyhorseriding,walkingandfishing.They’llmakeachangefromsittingbytheseasideandswimming.”
Hewrotetothefarmer.IntheletterhesaidthathewouldliketospendallofJulythere.ThenonthefirstofJuly,heleftforWestHillFarm.
Butfourdayslater,hereturnedhome.
“WhatwaswrongwithWestHillFarm?”hisbestfriend,Ed,askedhim.“Didn’tyouenjoycountrylife?”
“Countrylifewasverygood,”Henrysaid.“Buttherewasanotherproblem.”
“Oh.What?”
“Well,”hesaid,“thefirstdayIwasthereasheepdied,andwehadroastmuttonfordinner.”
“Whatswrongwiththat?”Edasked.“Freshmeatisthebest.”
“Iknow,butontheseconddayacowdied,andwehadroastbeeffordinner.”
“Luckyyou!”
“Youdontunderstand,”Henrysaid.“Onthethirddayapigdiedandwehadroastporkfordinner.”
“Adifferentmeateveryday,”Edsaidloudly,“andyouarecomplaining!”
“Letmefinish,”Henrysaid.“Onthefourthdaythefarmerdied,andIdidntdare(敢)stayfordinner!”
1.HowdidHenryfindoutaboutthefarm?
A.Hesawitinanewspaperadvertisement.B.Hisbestfriendtoldhim.
C.Hewrotetothefarmer.D.Maybehelearneditfromtheradio.
2.Henrycamebackhomeseveraldayslaterbecause______________.
A.hedidntlikethecountrylifeatallB.thefarmerwasn’tfriendlytohim
C.hisholidaywasoverD.hethoughthemighthavetoeatthefarmer
3.“…andyouarecomplaining!”,theword“complain”means__________.
A.夸奖B.说三道四C.抱怨D.故弄玄虚
4.Whichofthefollowingsentencesistrue?
A.Edcouldeatadifferentkindofmeateveryday.
B.Henrythoughthecouldenjoyachange.
C.Henrycouldntthinkofanythingelsetodo,sohewenttothefarm.
D.Thefarmerdiedbecauseofthebadmeatheate.
5.Whichisthebesttitleforthepassage?
A.Whatabeautifulfarm!B.Haveagoodtime.
C.AshortholidayD.Henryandthefarmer.
Passage14
Afterreturningfromherroundtrip,theangrywomanstoodoutsidetheticketofficeofthestation.“Therailwayowesme12pounds,”shesaidtoHarryJenks,theyoungmanworkingattheoffice.”YousoldmeaticketforMay22nd,buttherewasnoshipfromJerseythatnight.SomydaughterandIhadtostayinahotel.Itcostme12pounds.”
Harrywasworried.Herememberedsellingthewomanareturnticket.“Comeintotheoffice,Madam,”hesaidpolitely.“I’lljustchecktheJerseytimetableforMay22nd.”
Thewomanandherlittlegirlfollowedhiminside.Shewasquiteright,asHarrysoondiscovered.TherewasnosailingonMay22nd.Howcouldhehavemadesuchacarelessmistake?Heshouldn’thavesoldheraticketforthatday.Wonderingwhattodo,hesmiledatthechild.“Youlooksunburnt,”hesaidtoher.“DidyouhaveaniceholidayinJersey?”
“Yes,”sheanswered,shyly.“Thebeachwaslovely.AndIcanswimtoo!”
“That’sfine,”saidHarry.“Mylittlegirlcan’tswimabityet.Ofcourse,she’sonlythree…”
“I’mfour,”thechildsaidproudly.“I’llbefourandahalf.”
Harryturnedtothemother.“Irememberyourticket,Madam,”hesaid.“Butyoudidn’tgetoneforyourdaughter,didyou?”
“Er,well…”thewomanlookedatthechild.“Imean…shehasn’tstartedschoolyet,she’sonlyfour.”
“Afour-year-oldchildmusthaveaticket,Madam.Achild’sreturntickettoJerseycosts…letmesee…13.50pounds.Thelawisthelaw,butsincethemistakeismine….”
Thewomanstoodup,tookthechild’shandandlefttheoffice.
1.Thewomanwasangrybecause__________.
A.shecouldn’tusetheticketforherroundtrip
B.shehadtoreturnhomeadayearlierthanshehadplanned
C.shespentmoremoneythanshehadexpected
D.HarryhadsoldheratickettoJerseywheretherewasnosailing
2.Harrywasworried__________.
A.thewomanwasangrywithhim
B.hehadnotdonehisworkcarefully
C.theJerseytimetablewaswrong
D.thelittlegirldidn’thaveareturnticket
3.Harrystartedtalkingtothelittlegirl___________.
A.becausehewasintroubleanddidnotknowwhattodo
B.becausehehadalittlegirlaboutthesameageasthisgirl
C.becausehewantedtobefriendlytothelittlegirlwholookedsonice
D.whenhesuddenlyrealizedthathecouldfindawayoutfromthelittlegirl
4.WhenHarrysaid,“Thelawisthelaw,butsincethemistakewasmine…”hemeantthat______________.
A.theymustfollowitwithoutotherchoice,eventhoughthemistakewashis
B.hehadtobestrictwiththewomanbecauseofthelaw,althoughhedidn’twantto
C.thewomanhadtopayhim1.50poundsandtherailwaywouldpayherforthehotel
D.sheshouldpay1.50pounds,buthehadmadeamistake,shecouldgowithoutpaying
5.Thewomanlefttheofficewithoutsayinganythingbecause_______________.
A.shewantedtogohomeandgetmoneyforthechild’sticket
B.shewassoangrythatshedidn’twanttohaveanythingmoretodowiththeyoungman
C.shewasmoved(感动)byHarry’skindness
D.sheknewshewouldhavetopaytherailwayifsheinsisted(坚持)
Passage15
Threetravelers,Allan,CarlandPaulweresittingonthechairsinatrainstation.Theywerewaitingforatrainthatwasverylate.
Topassthetime,theybegantalkingtoeachother.
Atfirst,theytalkedabouttheweatherandtheirwork.ThenPaulsaid,"Tellme—whatwouldyoumostliketodoifyourdoctortellyouthatyouhaveonlythreemonthstolive?"
Theothertwomenthoughtaboutthisforawhile,thenCarlspoke.
“Well,”hesaid,“ifIhaveonlythreemonthstolive,I’lltakeallmymoneyoutofthebankandgotoforeigncountriesforholidayswithmybestfriend,Erik.Idliketotraveltotheplacesintheworldasmanyaspossible.AndIllstayatthebesthotelsandtheneatthebestfood.IthinkIllhaveawonderfultime.”
“Thatsveryinteresting.”Paulsaid.
Withthesewords,heturnedtotheotherman,saying,“Andwhataboutyou?”
“Illtellyouasecret,”Allansaid.“Ialwayswanttobearacingdriver.SoifIhaveonlythreemonthstolive,thefirstthingIdliketodoistosellmyhouse.WiththemoneyI’llbuythefastestcarintheworld.MaybeIcanenterallthebigmotorraces.”
Thenhelaughed,"Imightevenendup(以……而告终)worldchampion.”
“Nowitsyourturn,”Allanwenton,“Ifyourdoctortellyouthebadnews,whatwouldyoumostliketodo?”
“Oh,”saidPaulwithasmile.“I’llgoandseeanotherdoctor.”
1.Thethreemenweretalking_____________.
A.inthepostofficeB.inthewaitingroom
C.onthetrainD.onthechairs
2.Themancalled________answeredthequestionfirst.
A.CarlB.AllanC.ErikD.Paul
3.Themenbegantotalkabouttheweatherandtheworkbecausethey__________.
A.didntknowanythingnewB.wantedtopassthetimequickly
C.hadnothingtodoD.wereveryinterestedineachotherswork
4."Imightevenendupworldchampion."Heretheword"champion"means________inChinese.
A.名人B.赛车手C.大款D.冠军
5.Whichsentenceisrightaccordingtothepassage?
A.Thetraindidntarriveontime.
B.Paulwantedtobuyaracingcarverymuch.
C.Allanwasthesecondmantoanswerthequestion.
D.Carldidntliketravelingatall.
Researchers(研究者)haveannounced(宣布)theresultoftwostudiesonthehealtheffectsofthedrugaspirin(阿斯匹林).Onestudyshowsaspirincansharplyreducethechancethatahealthy,oldermanwillsufferfromaheartattack(心脏病).
Thestudyofferedtwonewresultsfromearlierfindings.Itsaidtakingoneaspirinpilleveryotherdayhelpedonlyhealthymenovertheageoffifty.Italsosaidaspiringavethegreatestprotectionagainstheartattackstomenwithlowbloodcholesterol(胆固醇)levels.
EarlierintheUnitedStatesbeganamajoraspirinstudyintheearly1980s.Itincluded22,000healthymendoctors.Allwerebetweentheagesoffortyandeighty-four.Morethan11,000ofthedoctorstookaharmlesspillthatcontainednodrug.Themendidnotknowwhichkindofpilltheyweretaking.
Thedoctorswhotookaspirinsuffered44%fewerheartattacksthanthosetakingtheharmlesspill.139menwhotookaspirinsufferedfromheartattacks.Tenofthemdied.239menwhodidnottakeaspirinsufferedfromheartattacks.Twenty-sixofthemdied.
Theresearcherssaidthedoctors’studyprovidesclearproofthattakingaspirincanpreventafirstheartattackinhealthy,oldermen.Theysaid,however,theresultdoesnotmeaneverymanovertheageoffiftyshouldtakeaspirin.Theysaidaspirincouldn’thelpmenwhodonoteathealthyfoods,whosmokecigarettesandwhoarefat.Theresearcherssaidmenwhothinktheywouldbehelpedbytakingaspirinshouldtalkwiththeirdoctorsfirst.
1.Thepassagetellsusthatthenewuseofaspirinis______.
A.totreatheartdisease
B.toreducepainwhileonesuffersfromaheartattack
C.tohelpoldpeopletobemorehealthy
D.toreducethechanceofaheartattackinoldmen
2.Aspirincanhelpthosewho______.
AworkasdoctorsB.areunder40yearsold
C.arefatandsmokecigarettesD.areolderandhealthy
3.Atlasttheresearchersadvisedustotakeaspirin______.
A.withcareB.asmuchaswelike
C.everydayD.onlyconsideringtheage
4.Fromtheexperimentwecanconcludethatabout_____ofpeoplewhosufferedfromheartattackswithoutaspirindied.
A.7%B.11%C.19%D.44%
Passage24
Itseemstobestrangetoyouthereisablindspot(盲点)ontheeyes.Hereisaninterestingexperiment(实验)thatcanmakesomethingdisappear,whenoneeyeisopen.
MakeacardaboutthesizeofapostcardandwritetwoEnglishlettersLandRonit,LontheleftandRontheright.First,holdthecardabout80cmawayandyouseeboththeletters.ThencloseyourrighteyeandlookattheletterRonlywithyourlefteye.Andnow,asyoumovethecardslowlytowardsyou,you’llfindtheletterLdisappearing.Butifyoumovethecardnearertoyourface,theletterwillbeseenagain.Nowdothesameexperimentwithyourlefteyeclosed,you’llfindtheletterRdisappearing.
Whydoestheletterdisappear?Itisbecausethereisablindspotontheeye.Whentheimage(影像)oftheletterfallsontheblindspot,itwon’tbeseen.Thatiswhyeitherofthelettersdisappears.
1.Thewriterofthepassagethinksthat_____thereisablindspotontheeye.
A.fewpeopleknowB.nooneknowsC.mostpeopleknowD.allthepeopleknow
2.Theword“disappear”inthepassagemeans________inChinese.
A.驱散B.消散C.消失D.遗失
3.YoufailtoseetheletterLintheexperimentbecause___________.
A.youreyesarepoorB.itsimagefallsontheblindspot
D.yourlefteyeisnotopenC.youmoveitclosetoyoureye
4.Inwhichorder(顺序)shouldyoudotheexperiment?
①Holdthecard②Movethecardnearer③Closeyourrighteye
④WritetwoEnglishletters⑤LookattheletterR⑥Makeacard
A.④⑥①②③⑤B.①③⑥④⑤②C.⑥①④③②⑤D.⑥④①③⑤②
5.Thepassagemainly(主要)tellsus_______.
A.howtofindtheblindspotB.aninterestingexperiment
C.wheretheblindspotisD.thereisblindspotontheeye
Passage25
Differentweathermakespeoplefeeldifferent.Itinfluences(影响)health,intelligence(智力)andfeelings.
InAugust,itisveryhotandwetinthesouthernpartoftheUnitedStates.Peopletherehavehearttroubleandotherkindsofhealthproblemsduringthismonth.IntheNortheastandtheMiddleWest,itisveryhotatsometimesandeverycoldatothertimes.PeopleinthesestateshavemorehearttroubleaftertheweatherchangesinFebruaryorMarch.
Theweathercanalsoinfluenceintelligence.Forexample,ina1983reportbyscientists,IQ(智商)ofagroupstudentswereveryhighwhenaverystrongwindcame,butafterthestrongwind,theirIQwas10%below.Thewindcanhelppeoplehavemoreintelligence.Veryhotweather,ontheotherhand(另一方面),canmakeitlower.StudentsinmanyschoolsoftheUnitedStatesoftengetworseonexamsinthehotmonthsoftheyear(JulyandAugust).
Weatheralsohasastronginfluenceonpeople’sfeelings.Wintermaybeabadtimeforthinpeople.Theyusuallyfeelcoldduringthesemonths.Theymightfeelunhappyduringcoldweather.Butfatpeoplemayhaveahardtimeinhotsummer.Atabout18C,peoplebecomestronger.
Lowairpressure(气压)maymakepeopleforgetful.Peopleleavemorebagsonbusesandinshopsonlow-pressuredays.Therearea“goodweather”forwordandhealth.Peoplefeelbestatatemperatureofabout18centigrade(摄氏度).
Areyoufeelingsad,tired,forgetful,orunhappytoday?Itmaybetheweather’sproblem.
1.____canhaveabadeffect(作用)onhealth.
A.HotandwetweatherB.Goodweather
C.WarmweatherD.Highintelligence
2.Peoplemayhavemoreintelligencewhen_____comes.
A.arainB.veryhotweather
C.astrongwindD.lowairpressure
3.Lowairpressuremaymakepeople_______.
A.forgetfulB.sadC.angryD.tired
4.In“goodweather”of18centigrade,_______.
A.peopleareveryforgetfulB.peoplecan’tdotheirworkwell
C.thinpeoplefeelcoldD.peopleareinbetterhealth
5.Thewriterwantstotellusthat_______.
A.hotandcoldweatherinfluencesallpeopleinthesameway
B.weatherinfluencespeople’slives
C.IQneverchangesduringweatherchanges
D.Thereisagoodkindofweatherforpeople’sworkandhealth
为了促进学生掌握上课知识点,老师需要提前准备教案,准备教案课件的时刻到来了。在写好了教案课件计划后,新的工作才会如鱼得水!你们知道哪些教案课件的范文呢?以下是小编为大家收集的“中考数学选择题解题方法专题复习导学案”但愿对您的学习工作带来帮助。
第1课时选择题解题方法
第一部分讲解部分
一.专题诠释
选择题是各地中考必考题型之一,2011年各地命题设置上,选择题的数目稳定在8~12题,这说明选择题有它不可替代的重要性.
选择题具有题目小巧,答案简明;适应性强,解法灵活;概念性强、知识覆盖面宽等特征,它有利于考核学生的基础知识,有利于强化分析判断能力和解决实际问题的能力的培养.
二.解题策略与解法精讲
选择题解题的基本原则是:充分利用选择题的特点,小题小做,小题巧做,切忌小题大做.
解选择题的基本思想是既要看到各类常规题的解题思想,但更应看到选择题的特殊性,数学选择题的四个选择支中有且仅有一个是正确的,又不要求写出解题过程.因而,在解答时应该突出一个“选”字,尽量减少书写解题过程,要充分利用题干和选择支两方面提供的信息,依据题目的具体特点,灵活、巧妙、快速地选择解法,以便快速智取,这是解选择题的基本策略.具体求解时,一是从题干出发考虑,探求结果;二是题干和选择支联合考虑或从选择支出发探求是否满足题干条件.事实上,后者在解答选择题时更常用、更有效.
三.考点精讲
考点一:直接法
从题设条件出发,通过正确的运算、推理或判断,直接得出结论再与选择支对照,从而作出选择的一种方法。运用此种方法解题需要扎实的数学基础.
例1.(2011广西省柳州市)九(3)班的50名同学进行物理、化学两种实验测试,经最后统计知:物理实验做对的有40人,化学实验做对的有31人,两种实验都做错的有4人,则这两种实验都做对的有()
A.17人B.21人C.25人D.37人
分析:设这两种实验都做对的有x人,根据九(3)班的50名同学进行物理、化学两种实验测试,经最后统计知:物理实验做对的有40人,化学实验做对的有31人,两种实验都做错的有4人可列方程求解.
解:设这两种实验都做对的有x人,(40﹣x)+(31﹣x)+x+4=50,x=25.故都做对的有25人.故选C.
评注:本题考查理解题意的能力,关键是以人数做为等量关系构造方程直接求解.
考点二:特例法
运用满足题设条件的某些特殊数值、特殊位置、特殊关系、特殊图形、特殊数列、特殊函数等对各选择支进行检验或推理,利用问题在某一特殊情况下不真,则它在一般情况下也不真的原理,由此判明选项真伪的方法。用特例法解选择题时,特例取得愈简单、愈特殊愈好.
例2.(2011浙江省宁波市)如图,⊙O1的半径为1,正方形ABCD的边长为6,点O2为正方形ABCD的中心,O1O2垂直AB于P点,O1O2=8.若将⊙O1绕点P按顺时针方向旋转360°,在旋转过程中,⊙O1与正方形ABCD的边只有一个公共点的情况一共出现()
A.3次B.5次C.6次D.7次
分析:根据⊙O1的半径为1,正方形ABCD的边长为6,点O2为正方形ABCD的中心,O1O2垂直AB于P点,设O1O2交圆O1于M,求出PM=4,得出圆O1与以P为圆心,以4为半径的圆相外切,即可得到答案.
解:∵⊙O1的半径为1,正方形ABCD的边长为6,点O2为正方形ABCD的中心,O1O2垂直AB于P点.
设O1O2交圆O1于M,∴PM=8﹣3﹣1=4,圆O1与以P为圆心,以4为半径的圆相外切,∴有5次.故选B.
评注:本题主要考查对直线与圆的位置关系,正方形的性质等知识点的理解和掌握,关注⊙O1与正方形ABCD的边只有一个公共点的几种极端情况,能求出圆的运动路线是解此题的关键.
考点三:筛选法(也叫排除法、淘汰法)
分运用选择题中单选题的特征,即有且只有一个正确选择支这一信息,从选择支入手,根据题设条件与各选择支的关系,通过分析、推理、计算、判断,对选择支进行筛选,将其中与题设相矛盾的干扰支逐一排除,从而获得正确结论的方法。使用筛选法的前提是“答案唯一”,即四个选项中有且只有一个答案正确.
例3.(2011广西省贺州市)函数y=ax﹣2(a≠0)与y=ax2(a≠0)在同一平面直角坐标系中的图象可能是()
A.B.C.D.
分析:由题意分情况进行分析:①当a>0时,抛物线开口向上,直线与y轴的负半轴相交,经过第一、三、四象限,②当a<0时,抛物线开口向下,直线与y轴的负半轴相交,经过第二、三、四象限.
解:∵在y=ax﹣2,∴b=﹣2,∴一次函数图象与y轴的负半轴相交.排除B、D.
∵①当a>0时,∴二次函数图象经过原点,开口向上,一次函数图象经过第一、三、四象限,选项A符合题意.
∵②当a<0时,∴二次函数图象经过原点,开口向下,一次函数图象经过第二、三、四象限,排除D.故选A.
评注:本题主要考查二次函数的图象、一次函数的图象,关键在于熟练掌握图象与系数的关系.
考点四:逆推代入法
将选择支中给出的答案或其特殊值,代入题干逐一去验证是否满足题设条件,然后选择符合题设条件的选择支的一种方法.在运用验证法解题时,若能据题意确定代入顺序,则能较大提高解题速度.
例4.(2011湖北省襄阳市)已知函数y=(k-3)x2+2x+1的图象与x轴有交点,则k的取值范围是()
A.k4B.k≤4C.k4且k≠3D.k≤4且k≠3
分析:注意到四个选择支中k=4与k=3这两个值是否满足已知条件可以区分出正确答案.
解:从四个选项入手,当k=3时,函数可化为y=2x+1,它的图象是一条直线,与x轴有一个交点(-,0),满足题意,排除选项C、D;当k=4时,函数可化为y=x2+2x+1,它的图象是抛物线,△=22-4×1×1=0,它与x轴有一个交点(-1,0),满足题意,排除A,选B.
评注:直接将各选项中的结论或者决定选项的特征数等代入题设条件进行验证,决定取舍,从而选出符合题意的答案.
考点五:直观选择法
利用函数图像或数学结果的几何意义,将数的问题(如解方程、解不等式、求最值,求取值范围等)与某些图形结合起来,利用直观几性,再辅以简单计算,确定正确答案的方法。这种解法贯穿数形结合思想,每年中考均有很多选择题(也有填空题、解答题)都可以用数形结合思想解决,既简捷又迅速.
例5.(2011湖北省随州市)已知函数y=,若使y=k成立的x值恰好有三个,则k的值为()
A.0B.1C.2D.3
分析:首先在坐标系中画出已知函数y=的图象,利用数形结合的方法即可找到使y=k成立的x值恰好有三个的k值.
解:函数y=的图象如图:
根据图象知道当y=3时,对应成立的x有恰好有三个,∴k=3.故选D.
评注:此题主要考查了利用二次函数的图象解决交点问题,解题的关键是把解方程的问题转换为根据函数图象找交点的问题.
考点六:特征分析法
对有关概念进行全面、正确、深刻的理解或根据题目所提供的信息,如数值特征、结构特征、位置特征等,提取、分析和加工有效信息后而迅速作出判断和选择的方法
例6.(2010浙江省绍兴市)如图,已知在直角梯形AOBC中,AC∥OB,CB⊥OB,OB=18,BC=12,AC=9,对角线OC、AB交于点D,点E、F、G分别是CD、BD、BC的中点,以O为原点,直线OB为x轴建立平面直角坐标系,则G、E、D、F四个点中与点A在同一反比例函数图象上的是()
A.点GB.点EC.点DD.点F
分析:反比例函数上的点的横纵坐标的乘积相等.根据题意和图形可初步判断为点G,利用直角梯形的性质求得点A和点G的坐标即可判断.
解:在直角梯形AOBC中
∵AC∥OB,CB⊥OB,OB=18,BC=12,AC=9
∴点A的坐标为(9,12)
∵点G是BC的中点
∴点G的坐标是(18,6)
∵9×12=18×6=108
∴点G与点A在同一反比例函数图象上,故选A.
评注:此题综合考查了反比例函数与一次函数的性质,此题难度稍大,综合性比较强,注意对各个知识点的灵活应用,灵活利用直角梯形的性质求得相关点的坐标,再利用反比例函数上的点的横纵坐标的乘积相等来判断.
考点七:动手操作法
与剪、折操作有关或者有些关于图形变换的试题是各地中考热点题型,只凭想象不好确定,处理时要根据剪、折顺序动手实践操作一下,动手可以直观得到答案,往往能达到快速求解的目的.
例7.(2011广东省广州市)如图所示,将矩形纸片先沿虚线AB按箭头方向向右对折,接着对折后的纸片沿虚线CD向下对折,然后剪下一个小三角形,再将纸片打开,则打开后的展开图是()
A.B.
C.D.
分析:严格按照图中的方法亲自动手操作一下,即可很直观地呈现出来,也可仔细观察图形特点,利用对称性与排除法求解.
解:∵第三个图形是三角形,
∴将第三个图形展开,可得,即可排除答案A,
∵再展开可知两个短边正对着,
∴选择答案D,排除B与C.故选D.
评注:本题主要考查学生的动手能力及空间想象能力.对于此类问题,学生只要亲自动手操作,答案就会很直观地呈现.
四.真题演练
1.(2011山东省威海市)二次函数y=x2﹣2x﹣3的图象如图所示.当y<0时,自变量x的取值范围是()
A.﹣1<x<3B.x<﹣1C.x>3D.x<﹣3或x>3
2.(2011浙江省衢州市)如图,一张半径为1的圆形纸片在边长为a(a≥3)的正方形内任意移动,则该正方形内,这张圆形纸片“不能接触到的部分”的面积是()
A.a2﹣πB.(4﹣π)a2C.πD.4﹣π
3.(2011湖北省随州市)如图,把Rt△ABC放在直角坐标系内,其中∠CAB=90°,BC=5,点A、B的坐标分别为(1,0)、(4,0),将△ABC沿x轴向右平移,当点C落在直线y=2x﹣6上时,线段BC扫过的面积为()
A.4B.8C.16D.8
4.(2011内蒙古呼和浩特市)已知一元二次方程x2+bx﹣3=0的一根为﹣3,在二次函数y=x2+bx﹣3的图象上有三点(-,y1)、(-,y2)、(,y3),y1、y2、y3的大小关系是()
A.y1<y2<y3B.y2<y1<y3C.y3<y1<y2D.y1<y3<y2
5.(2011广东省深圳市)如图,△ABC与△DEF均为等边三角形,O为BC、EF的中点,则AD:BE的值为()
A.:lB.:lC.5:3D.不确定
第二部分练习部分
1.(2011江苏省泰州市)如图,直角三角形纸片ABC的∠C为90°,将三角形纸片沿着图示的中位线DE剪开,然后把剪开的两部分重新拼接成不重叠的图形,下列选项中不能拼出的图形是()
A.平行四边形B.矩形C.等腰梯形D.直角梯形
2.(2011浙江省台州市)如图,双曲线y=与直线y=kx+b交于点M、N,并且点M的坐标为(1,3),点N的纵坐标为﹣1.根据图象信息可得关于x的方程=kx+b的解为
()
A.﹣3,1B.﹣3,3C.﹣1,1D.﹣1,3
3.(2011山东省威海市)如果不等式组的解集是x<2,那么m的取值范围是
()
A.m=2B.m>2C.m<2D.m≥2
4.(2011四川省资阳市)将一张正方形纸片如图所示折叠两次,并在上面剪下一个菱形小洞,纸片展开后是()
A.B.C.D.
5.(2011广西省柳州市)如图,在平行四边形ABCD中,EF∥AD,HN∥AB,则图中的平行四边形的个数共有()
A.12个B.9个C.7个D.5个
6.(2011内蒙古呼和浩特市)如图所示,四边形ABCD中,DC∥AB,BC=1,AB=AC=AD=2.则BD的长为()
A.B.C.3D.2
7.(2011江苏省苏州市)如图,巳知A点坐标为(5,0),直线y=x+b(b>0)与y轴交于点B,连接AB,∠α=75°,则b的值为()
A.3B.C.4D.
8.(2011陕西省)若二次函数y=x2﹣6x+c的图象过A(﹣1,y1),B(2,y2),C(3+,y3),则y1,y2,y3的大小关系是()
A.y1>y2>y3B.y1>y3>y2C.y2>y1>y3D.y3>y1>y2
9.(2011贵州省六盘水市)如图,在菱形ABCD中,对角线AC=6,BD=8,点E、F分别是边AB、BC的中点,点P在AC上运动,在运动过程中,存在PE+PF的最小值,则这个最小值是()
A.3B.4C.5D.6
10.(2011江苏省南通市)设m>n>0,m2+n2=4mn,则=()
A.2B.C.D.3
11.(2011陕西省)如图,过y轴上任意一点P,作x轴的平行线,分别与反比例函数y=和y=的图象交于A点和B点,若C为x轴上任意一点,连接AC,BC,则△ABC的面积为()
★“真题演练”参考答案★
1.【分析】先观察图象确定抛物线y=x2﹣2x﹣3的图象与x轴的交点,然后根据y<0时,所对应的自变量x的变化范围是-1<x<3.
【答案】选A
2.【分析】这张圆形纸片“不能接触到的部分”的面积是就是小正方形的面积与扇形的面积的差.小正方形的面积是:1;扇形BAO的面积是:.则这张圆形纸片“不能接触到的部分”的面积是4×1﹣4×=4﹣π.
【答案】D
3.【分析】根据题目提供的点的坐标求得点C的坐标为(1,4),当向右平移时,点C的纵坐标不变,代入直线求得点C的横坐标为1,进而求得其平移的距离为5-1=4,∴线段BC扫过的面积(平行四边形的面积)为4×4=16.
【答案】C
4.【分析】将x=﹣3代入x2+bx﹣3=0中,求b,得出二次函数y=x2+bx﹣3的解析式,再根据抛物线的对称轴,开口方向确定增减性,比较y1、y2、y3的大小关系.
【答案】A
5.【分析】连接OA、OD,∵△ABC与△DEF均为等边三角形,O为BC、EF的中点,∴AO⊥BC,DO⊥EF,∠EDO=30°,∠BAO=30°,∴OD:OE=OA:OB=:1,∵∠DOE+∠EOA=∠BOA+∠EOA即∠DOA=∠EOB,∴△DOA∽△EOB,∴OD:OE=OA:OB=AD:BE=:1.
【答案】A.
★“练习部分”参考答案★
1.【分析】将剪开的△ADE绕E点顺时针旋转180°,使EA与EB重合,得到矩形,也就是平行四边形,将剪开的△ADE绕D点逆时针旋转180°,使DA与DC重合,得到等腰梯形,故不能得到直角梯形.
【答案】D
2.【分析】首先把M点代入y=中,求出反比例函数解析式y=,再利用反比例函数解析式求出N点坐标(﹣3,﹣1),求关于x的方程=kx+b的解就是看一次函数与反比例函数图象交点横坐标就是x的值.
【答案】A
3.【分析】先解第一个不等式,再根据不等式组的解集是x<2,结合不等式组的解集,借助数轴可以得出关于m的不等式.
【答案】D
4.【分析】结合空间思维,分析折叠的过程及剪菱形的位置,注意图形的对称性,易知展开的形状.当正方形纸片两次沿对角线对折成为一直角三角形时,在垂直于斜边的位置上剪菱形,则直角顶点处完好,即原正方形中间无损,且菱形关于对角线对称.
【答案】C
5.【分析】根据平行四边形的定义:两组对边分别平行的四边形是平行四边形,则图中的四边DEOH、DEFC、DHGA、BGOF、BGHC、BAEF、AGOE、CHOF和ABCD都是平行四边形,共9个.
【答案】B
6.【分析】以A为圆心,AB长为半径作圆,延长BA交⊙A于F,连接DF.∵DC∥AB,∴=,∴DF=CB=1,BF=2+2=4,∵FB是⊙A的直径,∴∠FDB=90°,∴BD==.
【答案】B.
7.【分析】由直线y=x+b(b>0),可知∠1=45°,∵∠α=75°,∴∠ABO=180°﹣45°﹣75°=60°,∴OB=OA÷tan∠ABO=.∴点B的坐标为(0,),∴=0+b,b=.
【答案】B
8.【分析】根据二次函数图象上点的坐标特征,将A(﹣1,y1),B(2,y2),C(3+,y3)分别代入二次函数的解析式y=x2﹣6x+c求得y1,y2,y3,然后比较它们的大小并作出选择.
【答案】B
9.【分析】先根据菱形的性质求出其边长,再作E关于AC的对称点E′,连接E′F,则E′F即为PE+PF的最小值,再根据菱形的性质求出E′F的长度即可.
【答案】C
10.【分析】先根据m2+n2=4mn可得出(m2+n2)2=16m2n2,由m>n>0可知,>0,故可得出=,再把(m2﹣n2)2化为(m2+n2)2﹣4m2n2代入进行计算即可.
【答案】A
11.【分析】先设P(0,b),由直线APB∥x轴,则A,B两点的纵坐标都为b,而A,B分别在反比例函数y=和y=的图象上,可得到A点坐标为(﹣,b),B点坐标为(,b),从而求出AB的长,然后根据三角形的面积公式计算即可.
【答案】A
文章来源:http://m.jab88.com/j/88709.html
更多