www.1862.net > 已知菱形A1.B1.C1.D1边长为2,角A1.B1.C1=60°对角线...

已知菱形A1.B1.C1.D1边长为2,角A1.B1.C1=60°对角线...

=IF(OR(SUMPRODUCT(--(A1:C1>=5))

Sheet2表A1输入查询内容 B1公式=IF(A1="","",VLOOKUP($A1,Sheet1!$A:$D,COLUMN(B1),)) 右拉下拉

(Ⅰ)证明:由侧面AA1B1B为正方形,知AB⊥BB1.又∵AB⊥B1C,BB1∩B1C=B1,∴AB⊥平面BB1C1C,又∵AB?平面AA1B1B,∴平面AA1B1B⊥BB1C1C.(Ⅱ)由题意,CB=CB1,设O是BB1的中点,连接CO,则CO⊥BB1.由(Ⅰ)知,CO⊥平面AB1B1A,且CO=32BC=32AB=3.连接AB1...

分别构造△ABC与△A1B1C1如下:①作△ABC∽△A1B1C1,显然SS1=(aa1)2>1,即S>S1;②设a=b=101,c=20,则hc=1,S=10,a1=b1=c1=10,则S1=34×100>10,即S<S1;③设a=b=101,c=20,则hc=1,S=10,a1=b1=29,c1=10,则hc=2,S1=10,即S=S1;因此,S与S1...

是需要返回ABC列对应的行号吗? 在G1单元格输入以下数组公式,按Ctrl+Shift+Enter组合键结束 =MATCH(D1&E1&F1,A1:A50&B1:B50&C1:C50,0))

(I)连接CD1,∵直四棱柱ABCD-A1B1C1D1中,A1D1∥B1C1,A1D1=B1C1且B1C1∥BC,B1C1=BC∴四边形A1D1BC是平行四边形,可得CD1∥A1B∵△C1CD1中,EF是中位线,∴EF∥CD1∴EF∥A1B-----(3分)∵EF?面ABB1A1,A1B?面ABB1A1∴EF∥平面A1BD;…(6分)(II)连接AC与...

解答:解:如图,根据直观图画法的规则,直观图中A1D1∥O′y′,A1D1=1,?原图中AD∥Oy,从而得出AD⊥DC,且AD=2A1D1=2,直观图中A1B1∥C1D1,A1B1=23C1D1=2,?原图中AB∥CD,AB=23CD=2,即四边形ABCD上底和下底边长分别为2,3,高为2,如图.故其面积S...

=IF(A1=1,IF(B1>5000,IF(B1

连接C1B,∵E、F分别为C1D1与AB的中点,∴A1F=CE.又A1F∥CE,∴A1FCB为平行四边形,∴C1B∥EF.而C1B⊥B1C,∴EF⊥B1C.又四边形A1ECF是菱形,∴EF⊥A1C.∴EF⊥面A1B1C.又EF?平面A1ECF,∴平面A1B1C⊥平面A1ECF,∴B1在平面A1ECF上的射影在线段A1C上.∴∠B1A1C...

(1)证明:由正方体可得AB⊥平面BCC1B1,∴AB⊥B1C.由正方形BCC1B1可得B1C⊥BC1.而AB∩BC1=B,∴B1C⊥平面ABC1,∴B1C⊥AC1.同理可证,CD1⊥AC1,又CB1∩CD1=C,∴AC1⊥平面B1CD1;(2)∵CC1∥平面BB1D1D,∴点C1到平面BOD1的距离与点C到此平面的距离相等,...

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