范文一:某几何体的三视图
某几何体的三视图如图所示,其正视图,侧视图,俯视图均为全等的正方形,则该几何体的体积为( )
48626A. B. C. D. 33
2 2
2 2
2
2
6题图
已知一几何体的三视图如图所示,则该几何体的体积为 .
已知底面为正方形的四棱锥,其一条侧棱垂直于底面,那么该四棱锥的三视图可能是下列各图中的( )
2h,一个几何体的三视图如图所示,若该几何体的表面积为92m,则 m. of thiourea, and diluted to 100mL and mix. 31.5 trivalent arsenic (As3+) standard liquid weigh accurately arsenic trioxide 0.1320g, plus 100g/L 1mL and a small amount of potassium hydroxide sub-boiling distilled water dissolve into 100mL the bottle volume. This standard solution contains trivalent arsenic (As3+) 1mg/mL. Water level when using diluted to standard concentration for arsenic trivalent (As3+) 1 μg. Refrigerator use 7 days. 32 glass apparatus 15% nitrate soaked before using 24h. 32.1 atomic fluorescence spectrometer. 32.2, thermostatic water bath. 33 33.1 sample analysis steps deal with the body: learn from crushing 80 mesh sieve-like 2.50g (sample weight according to the content of the sample, as appropriate, increase or decrease) in 25mL graduated test tube. Add hydrochloric acid (1+1) solution 20mL, mixing, or 5.00g weigh fresh sample (sample should be homogenized into) in 25mL scale in a test tube, add 5mL hydrochloric acid and hydrochloric acid (1+1) solution diluted to scales, mixing。 At 60 ? c water bath 18h, shake the full extraction of the sample several times. Remove the cooling. Absorbent cotton filter, take the 4mL in a 10mL bottle of landfill leachate, mixed with potassium iodide-thiourea solution 1mL, n-octanol (antifoaming agent) 8 drops. Add water capacity. After placing 10min in test samples of inorganic arsenic. Such as turbidity, filtered again determined. Reagent blank at once. Note: the extraction of the sample after cooling. Before filtering with hydrochloric acid (1+1) solutions and sizing to 25mL. Liquid samples: the 4mL sample 10mL volumetric flask, Add hydrochloric acid (1+1) solution 4mL, Ki-thiourea solution 1mL 8
2一个几何体的三视图如图所示,若该几何体的表面积为92m,则. hm,______
一个几何体按比例绘制的三视图如右图所示(单位:),则该几何体的体积为( ) m
79793333A. B. C. D. mmmm3224
103一个几何体的三视图如图所示,已知这个几何体的体积为,则h________.
of thiourea, and diluted to 100mL and mix. 31.5 trivalent arsenic (As3+) standard liquid weigh accurately arsenic trioxide 0.1320g, plus 100g/L 1mL and a small amount of potassium hydroxide sub-boiling distilled water dissolve into 100mL the bottle volume. This standard solution contains trivalent arsenic (As3+) 1mg/mL. Water level when using diluted to standard concentration for arsenic trivalent (As3+) 1 μg. Refrigerator use 7 days. 32 glass apparatus 15% nitrate soaked before using 24h. 32.1 atomic fluorescence spectrometer. 32.2, thermostatic water bath. 33 33.1 sample analysis steps deal with the body: learn from crushing 80 mesh sieve-like 2.50g (sample weight according to the content of the sample, as appropriate, increase or decrease) in 25mL graduated test tube. Add hydrochloric acid (1+1) solution 20mL, mixing, or 5.00g weigh fresh sample (sample should be homogenized into) in 25mL scale in a test tube, add 5mL hydrochloric acid and hydrochloric acid (1+1) solution diluted to scales, mixing。 At 60 ? c water bath 18h, shake the full extraction of the sample several times. Remove the cooling. Absorbent cotton filter, take the 4mL in a 10mL bottle of landfill leachate, mixed with potassium iodide-thiourea solution 1mL, n-octanol (antifoaming agent) 8 drops. Add water capacity. After placing 10min in test samples of inorganic arsenic. Such as turbidity, filtered again determined. Reagent blank at once. Note: the extraction of the sample after cooling. Before filtering with hydrochloric acid (1+1) solutions and sizing to 25mL. Liquid samples: the 4mL sample 10mL volumetric flask, Add hydrochloric acid (1+1) solution 4mL, Ki-thiourea solution 1mL 8
某三棱椎的三视图如图所示,该三棱锥的四个面的面积中,最大的是( )
某几何体三视图如图1-1所示,则该几何体的体积为( )
ππA(8,2π B(8,π C(8, D(8, 24
图1-1
个多面体的三视图如图1-2所示,则该多面体的表面积为( )
A(21,3 B(8,2
C(21 D(18
of thiourea, and diluted to 100mL and mix. 31.5 trivalent arsenic (As3+) standard liquid weigh accurately arsenic trioxide 0.1320g, plus 100g/L 1mL and a small amount of potassium hydroxide sub-boiling distilled water dissolve into 100mL the bottle volume. This standard solution contains trivalent arsenic (As3+) 1mg/mL. Water level when using diluted to standard concentration for arsenic trivalent (As3+) 1 μg. Refrigerator use 7 days. 32 glass apparatus 15% nitrate soaked before using 24h. 32.1 atomic fluorescence spectrometer. 32.2, thermostatic water bath. 33 33.1 sample analysis steps deal with the body: learn from crushing 80 mesh sieve-like 2.50g (sample weight according to the content of the sample, as appropriate, increase or decrease) in 25mL graduated test tube. Add hydrochloric acid (1+1) solution 20mL, mixing, or 5.00g weigh fresh sample (sample should be homogenized into) in 25mL scale in a test tube, add 5mL hydrochloric acid and hydrochloric acid (1+1) solution diluted to scales, mixing。 At 60 ? c water bath 18h, shake the full extraction of the sample several times. Remove the cooling. Absorbent cotton filter, take the 4mL in a 10mL bottle of landfill leachate, mixed with potassium iodide-thiourea solution 1mL, n-octanol (antifoaming agent) 8 drops. Add water capacity. After placing 10min in test samples of inorganic arsenic. Such as turbidity, filtered again determined. Reagent blank at once. Note: the extraction of the sample after cooling. Before filtering with hydrochloric acid (1+1) solutions and sizing to 25mL. Liquid samples: the 4mL sample 10mL volumetric flask, Add hydrochloric acid (1+1) solution 4mL, Ki-thiourea solution 1mL 8
图1-2
在如图1-1所示的空间直角坐标系O ? xyz中,一个四面体的顶点坐标分别是(0,0,2),(2,2,0),(1,2,1),(2,2,2)(给出编号为?,?,?,?的四个图,则该四面体的正视图和俯视图分别为( )
图1-1
A(?和? B(?和? C(?和? D(?和?
一几何体的直观图如图1-1所示,下列给出的四个俯视图中正确的是( )
图1-1
A B C D
图1-2
几何体的三视图(单位:cm)如图1-1所示,则此几何体的表面积是( ) of thiourea, and diluted to 100mL and mix. 31.5 trivalent arsenic (As3+) standard liquid weigh accurately arsenic trioxide 0.1320g, plus 100g/L 1mL and a small amount of potassium hydroxide sub-boiling distilled water dissolve into 100mL the bottle volume. This standard solution contains trivalent arsenic (As3+) 1mg/mL. Water level when using diluted to standard concentration for arsenic trivalent (As3+) 1 μg. Refrigerator use 7 days. 32 glass apparatus 15% nitrate soaked before using 24h. 32.1 atomic fluorescence spectrometer. 32.2, thermostatic water bath. 33 33.1 sample analysis steps deal with the body: learn from crushing 80 mesh sieve-like 2.50g (sample weight according to the content of the sample, as appropriate, increase or decrease) in 25mL graduated test tube. Add hydrochloric acid (1+1) solution 20mL, mixing, or 5.00g weigh fresh sample (sample should be homogenized into) in 25mL scale in a test tube, add 5mL hydrochloric acid and hydrochloric acid (1+1) solution diluted to scales, mixing。 At 60 ? c water bath 18h, shake the full extraction of the sample several times. Remove the cooling. Absorbent cotton filter, take the 4mL in a 10mL bottle of landfill leachate, mixed with potassium iodide-thiourea solution 1mL, n-octanol (antifoaming agent) 8 drops. Add water capacity. After placing 10min in test samples of inorganic arsenic. Such as turbidity, filtered again determined. Reagent blank at once. Note: the extraction of the sample after cooling. Before filtering with hydrochloric acid (1+1) solutions and sizing to 25mL. Liquid samples: the 4mL sample 10mL volumetric flask, Add hydrochloric acid (1+1) solution 4mL, Ki-thiourea solution 1mL 8
图1-1 2222A(90 cm B(129 cm C(132 cm D(138 cm
某几何体的三视图如图1-2所示,则该几何体的表面积为( )
图1-2
A(54 B(60 C(66 D(72
of thiourea, and diluted to 100mL and mix. 31.5 trivalent arsenic (As3+) standard liquid weigh accurately arsenic trioxide 0.1320g, plus 100g/L 1mL and a small amount of potassium hydroxide sub-boiling distilled water dissolve into 100mL the bottle volume. This standard solution contains trivalent arsenic (As3+) 1mg/mL. Water level when using diluted to standard concentration for arsenic trivalent (As3+) 1 μg. Refrigerator use 7 days. 32 glass apparatus 15% nitrate soaked before using 24h. 32.1 atomic fluorescence spectrometer. 32.2, thermostatic water bath. 33 33.1 sample analysis steps deal with the body: learn from crushing 80 mesh sieve-like 2.50g (sample weight according to the content of the sample, as appropriate, increase or decrease) in 25mL graduated test tube. Add hydrochloric acid (1+1) solution 20mL, mixing, or 5.00g weigh fresh sample (sample should be homogenized into) in 25mL scale in a test tube, add 5mL hydrochloric acid and hydrochloric acid (1+1) solution diluted to scales, mixing。 At 60 ? c water bath 18h, shake the full extraction of the sample several times. Remove the cooling. Absorbent cotton filter, take the 4mL in a 10mL bottle of landfill leachate, mixed with potassium iodide-thiourea solution 1mL, n-octanol (antifoaming agent) 8 drops. Add water capacity. After placing 10min in test samples of inorganic arsenic. Such as turbidity, filtered again determined. Reagent blank at once. Note: the extraction of the sample after cooling. Before filtering with hydrochloric acid (1+1) solutions and sizing to 25mL. Liquid samples: the 4mL sample 10mL volumetric flask, Add hydrochloric acid (1+1) solution 4mL, Ki-thiourea solution 1mL 8
范文二:某几何体的三视图
1. 某几何体的三视图(单位:cm )如图所示,则此几何体的表面积是( )
A. 90cm B. 129cm C. 132cm D. 138cm
2
2
2
2
2. 某几何体的三视图如图所示, 则该几何体的体积为( )
ππ
(A )8-2π(B )8-π(C )8-(D )8-
24 3. 已知底面边长为1, 侧棱长为则该球的体积为 ( ) A.
B.4π C.2π D.
的正四棱柱的各顶点均在同一个球面上,
4. 某三棱锥的侧视图、俯视图如图所示,则该三棱锥的体积是( )(锥体体积公式:
V =
1
Sh
3,其中S 为底面面积,h 为高)
A .3 B.2 C
..1
5. 一个多面体的三视图如图所示,则多面体的体积是( )
4723
A. 3 B.6 C.6 D.7
如图,四棱锥P -ABCD 的底面边长为8的正方形,四条侧棱长均为2. 点G , E , F , H 分别是棱PB , AB , CD , PC 上共面的四点,平面GEFH ⊥平面
A B C D ,BC //平面GEFH .
(1)证明:GH //EF ;
(2)若EB =2,求四边形GEFH 的面积.
已知m , n 表示两条不同的直线, α表示平面, 下列说法正确的是 A. 若m ∥α,n ∥α, 则m ∥n C. 若m ⊥α,m ⊥n, 则n ∥α
B. 若m ⊥α,n ?α, 则m ⊥n D. 若m ∥α,m ⊥n, 则n ⊥α
若空间中四条两两不同的直线l 1, l 2, l 3, l 4满足l 1⊥l 2, l 2∥l 3, l 3⊥l 4, 则下列结论一定正确的是 ( )
A.l 1⊥l 4 B.l 1∥l 4
C.l 1与l 4既不垂直也不平行 D.l 1与l 4的位置关系不确定
如图, 在正方体ABCD-A 1B 1C 1D 1中,E,F,P,Q,M,N AB,AD,DD 1,BB 1,A 1B 1,A 1D 1的中点. 求证:
分别是棱
(1)直线BC 1∥平面EFPQ. (2)直线AC 1⊥平面PQMN.
如图1, 四边形ABCD 为矩形,PD ⊥平面ABCD,AB=1,BC=PC=2.作如图2折叠, 折痕EF ∥DC, 其中点E,F 分别在线段PD,PC 上, 沿EF 折叠后点P 叠在线段AD 上的点记为M, 并且MF ⊥
CF.
(1)证明:CF⊥平面MDF.
(2)求三棱锥M -CDE 的体积.
, CD ⊥BD 如图,三棱锥A -BCD 中,AB ⊥平面BCD .
(1)求证:CD ⊥平面ABD ;
(2)若AB =BD =CD =1,M 为AD 中点,求三棱锥A -MBC 的体积.
设m , n 是两条不同的直线,α, β是两个不同的平面( ) A.若m ⊥n ,n //α,则m ⊥α B.若m //β,β⊥α,则m ⊥α
C.若m ⊥β, n ⊥β, n ⊥α,则m ⊥α D.若m ⊥n ,n ⊥β,β⊥α,则m ⊥α 如图,四棱锥P -ABCD 中,AP ⊥
平面PCD , AD //BC ,
AB =BC =
1
AD 2, E , F 分
别为线段AD , PC 的中点. (Ⅰ)求证:AP //平面BEF (Ⅱ)求证:BE ⊥平面PAC
如图,四棱锥P -ABCD 的底面边长为8的正方形,四条侧棱长均为2. 点G , E , F , H 分别是棱PB , AB , CD , PC 上共面的四点,平面GEFH ⊥平面
ABCD ,BC //平面GEFH .
(3)证明:GH //EF ;
(4)若EB =2,求四边形GEFH 的面积.
在如图所示的多面体中,四边形ABB 1A 1和ACC 1A 1都为矩形. (1)若AC ⊥BC ,证明:直线BC ⊥平面ACC 1A 1;
(2)设D ,E 分别是线段BC ,CC 1的中点,在线段AB 上是否存在一点M ,使直线DE //平面A 1MC ?请证明你的结论.
一个四棱锥的侧棱长都相等,底面是正方形,其正(主)视图如图所示,
该四棱锥侧面积和体积分别是( )A.
B.
88
3
C.3 D. 8,8
某三棱锥的三视图如图所示,则该三棱锥的体积是( )
11
A.6 B.3
2
C .3 D.1
某四棱台的三视图如图所示,则该四棱台的体积是( )
1416
A .4 B.3 C.3 D.6
某几何体的三视图如图所示,则该几何体的体积为( )
560580
A. 3 B. 3 C. 200 D. 240
已知某几何体的三视图(单位:cm)如图所示, 则该几何体的体积是
)
(
A.108cm 3 B.100cm3 C.92cm 3 D.84cm3
已知正方体的棱长为1,其俯视图是一个面积为1的正方形,侧视图是一个
面积为 )
1
A .
B.1 C.2 D.一个几何体的三视图如图所示,则该几何体的直观图可以是( )
一个几何体的三视图如图所示,则该几何体可以是( )
A 棱柱 B棱台 C圆柱 D圆台 一几何体的三视图如右所示,则该几何体的体积为( )
A.200+9π B. 200+18π C. 140+9π D. 140+18π
某几何体的三视图如图所示, 则该几何体的体积为 ( )
A.16+8π B.8+8π C.16+16π D.8+16π
某几何体的三视图如图所示,则该几何体的体积是_______.
9
已知一个正方体的所有顶点在一个球面上. 若球的体积为2, 则正方体的
棱长为 .
若某几何体的三视图(单位:cm ) 如图所示, 则此几何体的体积等于 cm 3
.
某几何体的三视图如图所示, 则其体积为 .
某四棱锥的三视图如图所示,该四棱锥的体积为__________.
. ABC -A B C AB =AA ∠BAA =60CA =CB 11111如图,三棱柱中,,,
(Ⅰ)证明AB ⊥A 1C ;
(Ⅱ)若AB=CB=2, A1C= 求三棱柱ABC-A 1B 1C 1的体积
如图, 在四棱柱P ABCD 中,PD ⊥平面ABCD,AB ∥DC,AB
⊥
AD,BC=5,DC=3,AD=4,∠PAD=60°.
(1)M为PA 的中点, 求证DM ∥平面PBC. (2)棱锥D
PBC 的体积.
设l 为直线,α, β是两个不同的平面,下列命题中正确的是( ) A .若l //α,l //β,则α//β B.若l ⊥α,l ⊥β,则α//β C .若l ⊥α,l //β,则α//β D.若α⊥β,l //α,则l ⊥β
α, β是两个不同的平面,设m , n 是两条不同的直线,下列命题中正确的是( ) A.若α⊥β,m ?α, n ?β,则m ⊥n B.若α//β,m ?α, n ?β,则m //n C.若m ⊥n ,m ?α, n ?β,则α⊥β D.若m ⊥α,m //n ,n //β,则α⊥β
在下列命题中,不是公理的是 ( )
A. 平行于同一个平面的两个平面相互平行
B. 过不在同一条直线上的三点, 有且只有一个平面
C. 如果一条直线上的两点在一个平面内, 那么这条直线上所有的点都在此平面内
D. 如果两个不重合的平面有一个公共点, 那么它们有且只有一条过该点的公共直线
如图, 四棱柱ABCD -A 1B 1C 1D 1的底面ABCD 是正方形, O 为底面中心, A 1O ⊥
1=底面ABCD
, AB =AA
1
A
(Ⅰ) 证明: 平面A 1BD // 平面CD 1B 1; (Ⅱ) 求三棱柱ABD -A 1B 1D 1的体积.
如图,直三棱柱ABC -A 1B 1C 1中,D ,E 分别是AB ,BB 1的中点。
11; (1)证明:BC 1//平面ACD
(2)设AA 1=AC =CB =
2,AB =C -A 1DE 的体积。 已知m,n 为异面直线,m ⊥平面α,n ⊥平面β. 直线l 满足l ⊥m, l ⊥n, l ?α, l
?β, 则 ( ) A. α∥β且l ∥α B. α⊥β且l ⊥β
C. α与β相交, 且交线垂直于l D. α与β相交, 且交线平行于l
设m,n 是两条不同的直线, α, β是两个不同的平面 ( ) A. 若m ∥α,n ∥α, 则m ∥n B.若m ∥α,m ∥β, 则α∥β C. 若m ∥n,m ⊥α, 则n ⊥α D.若m ∥α, α⊥β, 则m ⊥β
如图,四棱锥P -ABCD 中,PA
⊥底面ABCD ,PA =,BC =CD =2,
∠ACB =∠
ACD =
π
3.
(Ⅰ)求证:BD ⊥平面PAC ;
(Ⅱ)若侧棱PC 上的点F 满足PF =7FC ,求三棱锥P -BDF 的体积.
D , E 分别是AB , AC 边上的点,AD =
AE ,如图①,在边长为1的等边?ABC 中,
F 是BC 的中点,AF 与DE 交于点G ,将?ABF 沿AF 折起,得到如图②所
BC =2. 示的三棱锥A -
BCF ,其中
(1) 证明:DE //平面BCF ;
(2) 证明:CF ⊥平面ABF ;
AD = ① ② (3) 当23时,求三棱锥F -DEG 的体积V F -DEG .
如图, AB 是圆O 的直径,PA 垂直圆O 所在的平面,C 是圆O 上的点.
(I) 求证:平面PAC ⊥平面PBC ;
(II) 设Q 为PA 的中点, G 为△AOC 的重心, 求证: QG ∥平面PBC
如图,四棱锥P -ABCD 中,∠ABC =∠BAD =90,BC =2AD , ?PAB 与?PAD 都是边长为2的等边三角形.
(I )证明:PB ⊥CD ;
(II )求点A 到平面PCD 的距离.
如图,在三棱柱ABC -A 1B 1C 中,侧棱AA 1⊥底面ABC ,AB =AC =2AA 1=2,∠BAC =120,D , D 1分别是线段BC , B 1C 1的中点,P 是线1段AD 上异于端点的点。 (1)在平面ABC 内,试作出过点P 与平面A 1BC 平行的
直线l ,说明理由,并证明直线l ⊥平面ADD 1A 1;
(2)设(1)中的直线l 交AC 于点Q ,求三棱锥A 1-QC 1D 的体积。(锥体V =1Sh 3,其中S 为底面面积,h 为高) 体积公式:
如图, 三棱柱ABC-A 1B 1C 1中, 侧棱A 1A ⊥底面ABC, 且各棱长均相等.D,E,F 分别
为棱AB,BC,A 1C 1的中点.
(1)证明EF ∥平面A 1CD.
(2)证明平面A 1CD ⊥平面A 1ABB 1.
如图, 在三棱锥S-ABC 中, 平面SAB ⊥平面SBC,AB ⊥BC,AS=AB,过A 作AF ⊥SB, 垂足为F, 点E,G 分别是棱SA,SC 的中点.
求证:(1)平面EFG ∥平面ABC.
(2)BC⊥SA.
如图,直四棱柱ABCD – A 1B 1C 1D 1中,AB//CD,AD ⊥AB ,AB=2,
AD=AA 1=3
,
E 为CD 上一点,DE=1,EC=3.
(1)证明:BE ⊥平面BB 1C 1C;
(2)求点B 1 到平面EA 1C 1 的距离.
如图,四棱锥P-ABCD 的底面ABCD 是边长为2的菱形,∠BAD=600。已知PB=PD=2,
PA=
(1)证明:PC ⊥BD
(2)若E 为PA 的中点,求三菱锥P-BCE 的体积。
如图,在四棱锥P-ABCD 中,AB ∥CD,AB ⊥AD,CD=2AB,平面PAD ⊥底面ABCD ,PA ⊥AD.E 和F 分别是CD 和PC 的中点,求证:
(Ⅰ)PA ⊥底面ABCD;
(Ⅱ)BE ∥平面PAD
(Ⅲ)平面BEF ⊥平面PCD.
P
F
C
D ,A B ⊥如图,四棱锥P -A B C 中D E A , C ⊥A B , P AB A ∥CD , AB =2CD ,
E , F , G , M , N 分别为PB , AB , BC , PD , PC 的中点
(Ⅰ) 求证:CE ∥平面PAD
(Ⅱ) 求证:平面EFG ⊥平面
EMN
下列命题正确的是( )
(A )若两条直线和同一个平面所成的角相等,则这两条直线平行
(B )若一个平面内有三个点到另一个平面的距离相等,则这两个平面平行
(C )若一条直线平行于两个相交平面,则这条直线与这两个平面的交线平行
(D )若两个平面都垂直于第三个平面,则这两个平面平行
范文三:已知某几何体的直观图和三视图如下图所示
已知某几何体的直观图和三视图如下图所示, 其正视图为矩形, 侧视图为等腰直角三角形, 俯视图为直角梯形. (Ⅰ) 证明:BN ⊥平面C 1B 1N ;
(Ⅱ) 设二面角C -NB 1-C 1的平面角为
,求cos 的值;
(Ⅲ)M 为AB 中点,在CB 上是否存在一点P ,使得MP ∥平面CNB 1,若存在,求出BP 的长; 若不存在,请说明理由.
本题主要考查三视图, 线面位置关系,二面角的求法等基本知识,考查空间想像能力,探索运算求解能力和推理论证能力. 满分13分.
法一:(Ⅰ) 证明∵该几何体的正视图为矩形, 侧视图为等腰直角三角形, 俯视图为直角梯形,
∴BA,BC,BB
1两两
垂直. ,以
BA,BC,BB 1分别为x , y , z 轴建立空间直角坐标系,……1分 则N(4,4,0),B1(0,8,0),C1(0,8,4),C(0,0,4)
∵=(4,4,0)·(-4,4,0)=-16+16=0, =(4,4,0)·(0,0,4)=0 ……3分
∴BN ⊥NB 1, BN⊥B 1C 1且NB 1与B 1C 1相交于B 1, ∴BN ⊥平面C 1B 1N; ……4分
(Ⅱ) ∵BN ⊥平面C 1B 1N, 是平面C 1B 1N 的一个,法向量=(4,4,0), ……5分,
设
=(x , y , z ) 为平面NCB 1的一个法向量,
则
,取=(1,1,2), …7分
则cos θ===; ……9分
(Ⅲ) ∵M(2,0,0).设P(0,0,a ) 为BC 上一点, 则=(-2,0,a ) ,∵MP ∥平面CNB 1,
∴⊥·=(-2,0,a ) ·(1,1,2)=-2+2 a =0 a =1. ……12分
又MP
平面CNB 1, ∴MP ∥平面CNB 1, ∴当BP=1时MP ∥平面CNB 1. ……14分
法二:(Ⅰ) 证明:由已知得B 1C 1⊥平面BNB 1, ∴B 1C 1⊥BN,
BN=4
= B1N,BB 1=8, ∴BB 12= BN2+ B1N 2, ∴BN ⊥B 1N ,又B 1C 1与B 1N 交于B 1, ∴BN ⊥平面C 1B 1N ;
(Ⅱ) 过N 作NQ B 1C 1, 则BCQN, 又BN ⊥平面C 1B 1N,
∴CQ ⊥平面C 1B 1N, 则CQ ⊥B 1N, QN⊥B 1N ,∴∠CNQ 是二面角C-B 1N-Q 的平面角θ, 在Rt △CNQ
中,NQ=4,CQ=4, ∴CN=4,cos θ==;
(Ⅲ) 延长BA 、B 1N 交于R, 连结CR, ∵MP ∥平面CNB 1, MP
平面CBR, 平面CBR∩平面CRN 于CR,
∴MP ∥CR, △RB 1B 中AN BB 1, ∴A 为RB 中点,
∴==, ∴BP=1,因此存在P 点使MP ∥平面CNB 1. ……14分
范文四:已知某几何体的直观图和三视图如下图所示研究报告
已知某几何体的直观图和三视图如下图所示, 其正视图为矩形,侧视图为等腰直角三角形,俯
视图为直角梯形. (?)证明:BN?平面CBN; 11
(?)设二面角C-NB-C的平面角为,求cos的值; 11
(?)M为AB中点,在CB上是否存在一点P,使得MP?平面CNB,若存在,求出BP的长;若不存在,请说明理1
由.
本题主要考查三视图,线面位置关系,二面角的求法等基本知识,考查空间想像能力,探索运算求解能力和推理论证能力.满分13分.
法一:(?)证明?该几何体的正视图为矩形,侧视图为等腰直角三角形,俯视图为直角梯形,?BA,BC,BB两两1垂直.,以BA,BC,BB分别为x,y,z轴建立空间直角坐标系,……1分 1
则N(4,4,0),B(0,8,0),C(0,8,4),C(0,0,4) 11
?=(4,4,0)?(-4,4,0)=-16+16=0, =(4,4,0)?(0,0,4)=0 ……3分 ?BN?NB, BN?BC且NB与BC相交于B, ?BN?平面CBN; ……4分 111111111
(?)?BN?平面CBN, 是平面CBN的一个,法向量=(4,4,0), ……5分, 1111
设=(x,y,z)为平面NCB的一个法向量, 1
则
,取=(1,1,2), …7分
则cosθ===; ……9分 (?)?M(2,0,0).设P(0,0,a)为BC上一点,则=(-2,0,a),?MP?平面CNB, 1???=(-2,0,a) ?(1,1,2)=-2+2 a =0 a =1. ……12分 又MP平面CNB, ?MP?平面CNB, ?当BP=1时MP?平面CNB. ……14分 111法二:(?)证明:由已知得BC?平面BNB,?BC?BN, 11111
222BN=4= BN,BB=8, ?BB= BN+ BN, ?BN?BN,又BC与BN交于B,?BN?平面CBN; 11111111111
(?)过N作NQBC,则BCQN,又BN?平面CBN, 1111
?CQ?平面CBN,则CQ?BN, QN?BN ,??CNQ是二面角C-BN-Q的平面角θ,在Rt?CNQ11111中,NQ=4,CQ=4, ?CN=4,cosθ==;
(?)延长BA,BN交于R,连结CR,?MP?平面CNB, 11
MP平面CBR, 平面CBR?平面CRN于CR,
?MP?CR, ?RBB中ANBB,?A为RB中点, 11
?==,?BP=1,因此存在P点使MP?平面CNB. ……14分 1
范文五:已知某个几何体的三视图如下
王新敞特级教师源头学子小屋http://wxc.833200com.wxckt@126com.新疆奎屯?2007?8 已知某个几何体的三视图如下,根据图中标出的
尺寸(单位:cm),可得这个几何体的体积是( )
2040003王新敞特级教师源头学子小屋http://wxc833200.com.wxckt@126.com新疆奎屯?2007?, cm 3
80003王新敞特级教师源头学子小屋http://wxc833200.com.wxckt@126.com新疆奎屯?2007?, cm20203
正视图 侧视图 3王新敞特级教师源头学子小屋http://wxc833200.com.wxckt@126.com新疆奎屯?2007?, 2000cm
3王新敞特级教师源头学子小屋http://wxc833200.com.wxckt@126.com新疆奎屯?2007?, 4000cm10
10
20
俯视图