- 问题详情:如图,四棱锥P-ABCD中,侧面PAD为等比三角形且垂直于底面ABCD,E是PD的中点.(1)*:直线平面PAB(2)点M在棱PC上,且直线BM与底面ABCD所成锐角为,求二面角M-AB-D的余弦值 【回答】【解析】(1)令中点为,连结,,.∵,为,中点,∴为的中位线,∴.又∵,∴.又∵,∴,∴.∴四边形为平行四边形,∴.又∵,∴(2)以中点...
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- 问题详情:如图,在四棱锥P-ABCD中,底面ABCD为菱形,△PAD为正三角形,平面PAD上平面ABCD,E,F分别是AD,CD的中点. (I)*:BD⊥平面PEF; (Ⅱ)若∠BAD=60°,求二面角B-PD-A的余弦值.【回答】知识点:空间几何体题型:解答题...
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- 1、Theminutestickedby.Bobscribbledawayonthepad.2、Willbeflatonthecorrugatedboardflatonthepad.3、Giventhefactthatthetargetsiteis580kilometersfromShuangchengzi,itispossiblethataDF-15CtestseriesresultedintheHEimpactsonthepad....
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- Hoptothatlilypadinthesky,oldfriend.AgreenfrogsitsatopalargelilypadinthewatersofAtchafalayaDelta.WhenCharleysawWandahejumpedontoalilypad."Hi,"hecried.Hewasahandsomeprincebutawetone.Thelilypadhadcollapsedunderhisweightanddumpedhimintothewater.Oilspil...
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- 问题详情:如图,四棱锥P-ABCD中,侧面PAD是边长为2的等边三角形且垂直于底,,,是的中点。(1)*:直线平面;(2)点在棱上,且直线与底面所成角为,求二面角的余弦值。【回答】【解析】试题分析:(1)取的中点,连结,,由题意*得∥,利用线面平行的判断定理即可*得结论;(2)建立空间直角坐标系,求得半平面的法向量...
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- 问题详情:已知四棱锥P-ABCD的顶点都在球O上,底面ABCD是矩形,平面PAD⊥平面ABCD,△PAD为正三角形,AB=2AD=4,则球O的表面积为()A. B. C.24π D.【回答】B令△PAD所在圆的圆心为O1,则易得圆O1的半...
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- fixingofshoulderpadThepadisimpregnatedwithinsecticide.Neverpadoutyouressaywithirrelevantdetails.Startbynotbuyingyourselfasketchpad.Sheseesthestamppadonmysweater.Amongthosewhohandledahottherapeuticpad,54%chosethevoucherforafriend,butonly25%ofthosewhoh...
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- Scrubeachopticalsurfacewithagauzepadsoakedinacetone.Ihadtopayrushshippingformybirthkit—allthesterilizedgauzepads,alcoholswabs,glovesandgoopthemidwifeneedsatthebirth.Firstaidkit.Itshouldhavelatexgloves,gauzepads,thermometer,sterilebandages,band-aids,...
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- telephonenumBerswrittenonapadShewroteonapadofpaper.NexttoPaulsen,NimGoldmandoodledthoughtfullyonapad.Heputonapadofgauzeandastripofadhesivetapeoverthewound.Mobilehomeortrailersmaybeonapadwhichyourentinamobilehomepark.Thechipsstorepersonaldatathatcanbe...
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- LateMondayafternoon,readingtheobscureandintricatemarkings,theyidentifiedalaunchingpad.Thecenterpiecewasanornatemodelrocketonagreenfaunalaunchingpad.UponreturningtoEngland,heemployedthefavorablemediaattentionasalaunchingpadforhisforayintopolitics.Usin...
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- 问题详情:如图,在四棱锥P﹣ABCD中,底面ABCD是边长为2的正方形,侧面PAD⊥底面ABCD,且PA=PD=AD,E、F分别为PC、BD的中点.(Ⅰ)求*:EF∥平面PAD;(Ⅱ)求*:面PAB⊥平面PDC;(Ⅲ)在线段AB上是否存在点G,使得二面角C﹣PD﹣G的余弦值为?说明理由.【回答】【考点】平面与平面垂直的判定;直线与平面平行的判定;二...
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- Thespaceshipwillliftofffromthelaunchingpadat7a.m.Thecenterpiecewasanornatemodelrocketonagreenfaunalaunchingpad.Usingthegrantfundingasalaunchingpad,projectsoftengoontoscaleuporreplicateelsewhere,winningprestigiousawardswithinthesphereofsocialentrepren...
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- Thereportersreportedthatthelaunchpadwasonfireafterthelaunch.Themilitaryhasnotbeenabletodeterminetheexactlocationofthelaunchpad.Therocketexplodedonthelaunchpad,burningaliveandasphyxiatingengineers,designersandofficials.Thatlaunchmarkedtheinaugurationo...
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- 问题详情:如图,在四棱锥P-ABCD中,底面ABCD为正方形,平面PAD⊥平面ABCD,点M在线段PB上,PD//平面MAC,PA=PD=,AB=4.(I)求*:M为PB的中点;(II)求二面角B-PD-A的大小;(III)求直线MC与平面BDP所成角的正弦值.【回答】(Ⅰ)详见解析:(Ⅱ);(Ⅲ)【解析】试题解析:解:(I)设交点为,连接.因为平面,平面平面,所以.因为是正...
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- 问题详情:已知定点A(3,4),点P为抛物线y2=4x上一动点,点P到直线x=-1距离为d,则|PA|+d的最小值为( )A. B.2 C. D.【回答】A知识点:圆锥曲线与方程题型:选择题...
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- Avoidingputtingyourelbowonhardsurfacesmayhelp,orwearinganelbowpadovertheulnarnerveand"funnybone"mayhelp.MayIborrowyourkneepadsandelbowpads?Ofcourse,besuretheyhaveonprotectivegear,includingahelmet,kneepadsandelbowpads....
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- Startbynotbuyingyourselfasketchpad.Comparedtothephonologicalloopandthevisuospatialsketchpad,thecentralexecutivemayhaveakeyroleinchildren'sarithmeticcognition.Comparedtothephonologicalloopandthevisuospatialsketchpad,thecentralexecutivemayhaveakeyrole...
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- Whentypingonakeyboard,shouldbethewristpad,avoidwiththeforearmraised.Ensurethattheactivityisageappropriateandprovideprotectiveequipmentsuchashelmets,wristpads,andkneepads....
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- 问题详情:如图,四棱锥P-ABCD中,侧面PAD是边长为2的等边三角形且垂直于底,是的中点.(1)*:直线平面;(2)点在棱上,且直线与底面所成角为,求二面角的余弦值.【回答】(1)见解析;(2)【详解】试题分析:(1)取的中点,连结,,由题意*得∥,利用线面平行的判断定理即可*得结论;(2)建立空间直角坐标系,求得半平面的法...
- 23082
- Asanitarybreastpadrelatestothetechnicalfieldofwomanhealth-carearticles,inparticulartoasanitarypadusedforkeepingthecircumferenceandclothesdryforwomeninlactationperiod.Forexample,mostgirlsinKatinecannotaffordsanitarypadsorachangeofclothes.Advertisingsa...
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- Helostallhismoneyandhadtopadithome.Ididn'tbuysilkthread.Letherpaditfirst.Embroideryisthesameasyours.Howmuchisthemanualcostofembroidery?...
- 17421
- 问题详情: 如图,在四棱锥P-ABCD中,底面ABCD为平行四边形,己知AP=AC=AB=2,∠PAD=∠DAC=60°.(1)求*:AD丄PC;(2)若平面PAD丄平面ABCD,求二面角C-PD-A的余弦值.【回答】知识点:点直线平面之间的位置题型:解答题...
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- 问题详情:如图,在四棱锥P﹣ABCD中,侧面PAD是正三角形,且与底面ABCD垂直,底面ABCD是边长为2的菱形,∠BAD=60°,N是PB的中点,过A、D、N三点的平面交PC于M,E为AD的中点,求*:(1)EN∥平面PDC;(2)BC⊥平面PEB;(3)平面PBC⊥平面ADMN.【回答】解:(1)∵AD∥BC,AD⊂平面ADMN,BC⊄平面ADMN, ∴BC∥平...
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- 问题详情:如图,在四棱锥P-ABCD中,侧面PAD为正三角形,底面ABCD为正方形,侧面PAD⊥底面ABCD,M为底面ABCD内的一个动点,且满足MP=MC,则点M在正方形ABCD内的轨迹为下图中的【回答】A知识点:空间几何体题型:选择题...
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- Shesmasheditusingthephone'sspecial'SWYPE'keypad,whichenablesuserstoinputtextwithouttheirfingertipleavingthescreen.Inwordprocessing,aseparatesetofkeysnumbered0through9onawordprocessor'skeyboardthatallowseasyentryofnumbers,aligningthemautomatically...
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