問題詳情:如圖,四稜錐P-ABCD中,底面ABCD為矩形,側面PAD為正三角形,且平面PAD⊥平面ABCD,E為PD中點,AD=2.(1)求*:平面AEC⊥平面PCD;(2)若二面角A-PC-E的平面角大小θ滿足,求四稜錐P-ABCD的體積. ...
2021-02-04 29256
Avoidingputtingyourelbowonhardsurfacesmayhelp,orwearinganelbowpadovertheulnarnerveand"funnybone"mayhelp.MayIborrowyourkneepadsandelbowpads?Ofcourse,besuretheyhaveonprotectivegear,includingahelmet,kneepadsandelbowpads....
2018-08-17 7358
Hoptothatlilypadinthesky,oldfriend.AgreenfrogsitsatopalargelilypadinthewatersofAtchafalayaDelta.WhenCharleysawWandahejumpedontoalilypad."Hi,"hecried.Hewasahandsomeprincebutawetone.Thelilypadhadcollapsedunderhisweightanddumpedhimintothewater.Oilspil...
2018-07-28 24943
問題詳情:小明喜歡利用pad聽歌,根據聲音的(選填“音調”、“響度”或“音*”)就判斷出是哪位歌手;音量太大會使耳膜受損,説明聲能傳遞 (“信息”或“能量”),為此需要減小聲音的 (“音調”、“響度”或“音*”).【回答】【分析】聲音不但能傳遞信息,還能夠傳遞能量;聲音的三個特徵分...
2020-10-19 26896
問題詳情:在四稜錐P-ABCD中,AD∥BC,,G是PB的中點,△PAD是等邊三角形,平面PAD⊥平面ABCD.(Ⅰ)求*:CD⊥平面GAC;(Ⅱ)求二面角P-AG-C的正弦值.【回答】知識點:點直線平面之間的位置題型:解答題...
2020-05-16 9872
問題詳情:如圖,在四稜錐中,O為AC與BD的交點,平面PAD,是正三角形,,. (1)若點E為稜PA上靠A近的三等分點,*:直線平面PBC; (2)求*:平面平面PDC. 【回答】*: (1)因為,,所以.……………2分點E為稜PA上靠A近的三等分點,即,所以,.………………4分又因為平面PBC,平面PBC,所以...
2021-08-28 5579
Whentypingonakeyboard,shouldbethewristpad,avoidwiththeforearmraised.Ensurethattheactivityisageappropriateandprovideprotectiveequipmentsuchashelmets,wristpads,andkneepads....
2018-07-26 27022
問題詳情:如圖,四稜錐P-ABCD中,側面PAD為等邊三角形且垂直於底面ABCD,AB=BC=AD,∠BAD=∠ABC=90°。(1) *:直線BC∥平面PAD;(2) 若△PAD面積為2,求四稜錐P-ABCD的體積。【回答】(1)*:∵底面中,∴又平面,平面,∴平面.(2)∵側面是等邊三角形,且垂直於底面,∴中邊上的高也...
2021-02-27 31853
Startbynotbuyingyourselfasketchpad.Comparedtothephonologicalloopandthevisuospatialsketchpad,thecentralexecutivemayhaveakeyroleinchildren'sarithmeticcognition.Comparedtothephonologicalloopandthevisuospatialsketchpad,thecentralexecutivemayhaveakeyrole...
2018-03-26 32956
1、scratchpadmemory2、scratchpadregister3、DoyouhaveascratchpadIcanwriteon?4、Theinventionrelatestoamulticolorscratchpad,acollatingmethodthereofandamulticolorscratchpadcollatingmachine....
2024-02-23 5145
Thereportersreportedthatthelaunchpadwasonfireafterthelaunch.Themilitaryhasnotbeenabletodeterminetheexactlocationofthelaunchpad.Therocketexplodedonthelaunchpad,burningaliveandasphyxiatingengineers,designersandofficials.Thatlaunchmarkedtheinaugurationo...
2016-10-17 10236
Scrubeachopticalsurfacewithagauzepadsoakedinacetone.Ihadtopayrushshippingformybirthkit—allthesterilizedgauzepads,alcoholswabs,glovesandgoopthemidwifeneedsatthebirth.Firstaidkit.Itshouldhavelatexgloves,gauzepads,thermometer,sterilebandages,band-aids,...
2018-09-30 5982
問題詳情:如圖,在四稜錐P-ABCD中,側面PAD為正三角形,底面ABCD為正方形,側面PAD⊥底面ABCD,M為底面ABCD內的一個動點,且滿足MP=MC,則點M在正方形ABCD內的軌跡為( ) A. B. C. ...
2019-10-25 21303
問題詳情:如圖,四稜錐P-ABCD中,側面PAD是邊長為2的等邊三角形且垂直於底,是的中點.(1)*:直線平面;(2)點在稜上,且直線與底面所成角為,求二面角的餘弦值.【回答】(1)見解析;(2)【詳解】試題分析:(1)取的中點,連結,,由題意*得∥,利用線面平行的判斷定理即可*得結論;(2)建立空間直角座標系,求得半平面的法...
2020-09-14 23082
CleaningProductSeriesisincludingspecialscouringpad,spongescouringpadandmultifunctionalscrubbrush.Roundsupplyofnylonabrasivepolishingabrasives,includinggrindingwheels,wingstoflyround,grindingdiscs,grindingwheelsspecialrelief,suchasscouringpad....
2022-08-10 32161
telephonenumBerswrittenonapadShewroteonapadofpaper.NexttoPaulsen,NimGoldmandoodledthoughtfullyonapad.Heputonapadofgauzeandastripofadhesivetapeoverthewound.Mobilehomeortrailersmaybeonapadwhichyourentinamobilehomepark.Thechipsstorepersonaldatathatcanbe...
2022-03-24 8994
問題詳情:已知四稜錐P-ABCD的頂點都在球O上,底面ABCD是矩形,平面PAD⊥平面ABCD,△PAD為正三角形,AB=2AD=4,則球O的表面積為()A. B. C.24π D.【回答】B令△PAD所在圓的圓心為O1,則易得圓O1的半...
2021-06-03 31138
Thespaceshipwillliftofffromthelaunchingpadat7a.m.Thecenterpiecewasanornatemodelrocketonagreenfaunalaunchingpad.Usingthegrantfundingasalaunchingpad,projectsoftengoontoscaleuporreplicateelsewhere,winningprestigiousawardswithinthesphereofsocialentrepren...
2018-05-17 18086
問題詳情:如圖,四稜錐P-ABCD中,側面PAD為等比三角形且垂直於底面ABCD,E是PD的中點.(1)*:直線平面PAB(2)點M在稜PC上,且直線BM與底面ABCD所成鋭角為,求二面角M-AB-D的餘弦值 【回答】【解析】(1)令中點為,連結,,.∵,為,中點,∴為的中位線,∴.又∵,∴.又∵,∴,∴.∴四邊形為平行四邊形,∴.又∵,∴(2)以中點...
2022-04-19 10974
問題詳情:如圖,四稜錐中,側面PAD為等邊三角形且垂直於底面ABCD,E是PD的中點.(1)*:直線平面PAB(2)點M在稜PC上,且直線BM與底面ABCD所成鋭角為,求二面角的餘弦值 【回答】知識點:點直線平面之間的位置題型:解答題...
2020-10-22 21489
問題詳情:如圖,在四稜錐P﹣ABCD中,側面PAD是正三角形,且與底面ABCD垂直,底面ABCD是邊長為2的菱形,∠BAD=60°,N是PB的中點,過A、D、N三點的平面交PC於M,E為AD的中點,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...
2019-11-26 31265
問題詳情:已知定點A(3,4),點P為拋物線y2=4x上一動點,點P到直線x=-1距離為d,則|PA|+d的最小值為( )A. B.2 C. D.【回答】A知識點:圓錐曲線與方程題型:選擇題...
2020-06-28 26657
問題詳情: 如圖,在四稜錐P-ABCD中,側面PAD為正三角形,底面ABCD為正方形,側面PAD⊥底面ABCD,M為底面ABCD內的一個動點,且滿足MP=MC,則點M在正方形ABCD內的軌跡為( )A. B. C. D.【回答】A【解析】試題分析:根據題意可知PD=DC,則點D符合“M為底面ABCD內的一...
2019-09-04 29070
問題詳情:.如圖,四稜錐P-ABCD中,側面PAD為等邊三角形且垂直於底面ABCD,AB=BC=AD,∠BAD=∠ABC=90°,E是PD的中點.(1)*:直線CE∥平面PAB;(2)點M在稜PC上,且直線BM與底面ABCD所成角為45°,求二面角M-AB-D的餘弦值.【回答】.(1)*取PA的中點F,連接EF,BF.因為E是PD的中點,所以EF...
2019-09-21 9839
問題詳情: 如圖,在四稜錐P-ABCD中,底面ABCD為平行四邊形,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的餘弦值.【回答】知識點:點直線平面之間的位置題型:解答題...
2020-04-30 26988