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CBSE Questions for Class 12 Commerce Maths Three Dimensional Geometry Quiz 11 - MCQExams.com

If AB=21, B(2,1,8) and the direction cosines of AB are 67,27,37 then the coordinates of A are
  • (16,7,1)
  • (20,5,17)
  • (16,7,1)
  • (20,5,17)
The direction ratios of the normal to the plane through (1,0,0) and (0,1,0) which makes an angle of \dfrac{\pi }{4} with the plane x + y = 3 are-
  • 1,\sqrt {2},1
  • 1,1,\sqrt {2}
  • 1,1,2
  • \sqrt {2},1,1
If {l}_{1},{m}_{1},{n}_{1} and {l}_{2},{m}_{2},{n}_{2} are the d.c.s of the two lines, then {({l}_{1}{l}_{2}+{m}_{1}{m}_{2}+{n}_{1}{n}_{2})}^{2}+{({l}_{1}{m}_{2}-{l}_{2}{m}_{1})}^{2}+{({m}_{1}{n}_{2}-{m}_{2}{n}_{1})}^{2}+{({n}_{1}{l}_{2}-{n}_{2}{l}_{1})}^{2}=
  • 3
  • 2
  • 1
  • 4
If P=(0,1,2),Q=(4,-2,1),O=(0,0,0) then \angle POQ=
  • \dfrac{\pi}{6}
  • \dfrac{\pi}{4}
  • \dfrac{\pi}{3}
  • \dfrac{\pi}{2}
If a line makes angles \alpha, \beta, \gamma with positive axes, then the range of \sin{\alpha}\sin{\beta}+\sin{\beta} \sin{\gamma} +\sin{\gamma} \sin {\alpha} is
  • \left(\dfrac{-1}{2},1\right)
  • \left(\dfrac{1}{2},2\right)
  • (-1,2)
  • (-1,2]
If the angle between the lines, \dfrac { x }{ 2 } =\dfrac { y }{ 2 } =\dfrac { z }{ 1 } and \dfrac { 5-x }{ -2 } =\dfrac { 7y-14 }{ P } =\dfrac { z-3 }{ 4 } is \cos { ^{ -1 }\left( \dfrac { 2 }{ 3 }  \right)  } , then p is equal to: 
  • -\dfrac { 4 }{ 7 }
  • \dfrac { 7 }{ 2 }
  • -\dfrac { 7 }{ 4 }
  • \dfrac { 2 }{ 7 }
The direction cosines of the line which is perpendicular to the lines whose direction cosines are proportional to ( 1, -1,2 ) and ( 2,1,-1) are:- 
  • \frac { 1 }{ \sqrt { 35 } } ,-\frac { 5 }{ \sqrt { 35 } } ,\frac { 3 }{ \sqrt { 35 } }
  • -\frac { 1 }{ \sqrt { 35 } } ,\frac { 5 }{ \sqrt { 35 } } ,\frac { 3 }{ \sqrt { 35 } }
  • \frac { 1 }{ \sqrt { 35 } } ,\frac { 5 }{ \sqrt { 35 } } ,\frac { 3 }{ \sqrt { 35 } }
  • none of these
If (2,1,3) and (-1,2,4) are the extermities of a diagonal of a rhombus then the d.r's of the other diagonal are
  • (2,3,-9)
  • (-2,3,-9)
  • (1,-2,4)
  • (2,3,1)
The direction cosines of the line which is perpendicular to the lines whose direction cosines are proportional to (1, -1, 2) and (2, 1, -1) are
  • \dfrac{-1}{\sqrt{35}}, \dfrac{5}{\sqrt{35}}, \dfrac{3}{\sqrt{35}}
  • \dfrac{13}{\sqrt{35}}, \dfrac{-1}{\sqrt{35}}, \dfrac{1}{\sqrt{35}}
  • \dfrac{2}{\sqrt{3}}, \dfrac{5}{\sqrt{3}}, \dfrac{7}{\sqrt{3}}
  • \dfrac{3}{\sqrt{35}}, \dfrac{5}{\sqrt{35}}, \dfrac{7}{\sqrt{35}}
A mirror and source of light are kept at the origin and the positive x-axis respectively a ray a light from the sources strikes the mirror and is reflected. If (1,-1,1) are the Dr's of a normal to the plane. Then the D.C's of the reflected ray are 
  • (\frac{-1}{3},\frac{-2}{3},\frac{2}{3})
  • (\frac{1}{3},\frac{2}{3},\frac{2}{3})
  • (\frac{1}{3},\frac{-2}{3},\frac{2}{3})
  • (\frac{-1}{3},\frac{2}{3},\frac{2}{3})
If the incident ray and normal have the directions of the vectors \left(1,-3,1\right),\left(1,1,1\right) respectively, then direction of the reflected ray is-
  • \left(4,-8,4\right)
  • \left(5,-7,5\right)
  • \left(6,-6,6\right)
  • \left(-5,7,5\right)
The direction cosines of the line which is perpendicular to the lines whose direction cosines are proportional to (1,-1,2) and (2,1,-1) are:- 
  • \frac { 1 }{ \sqrt { 35 } } ,-\frac { 5 }{ \sqrt { 35 } } ,\frac { 3 }{ \sqrt { 35 } }
  • -\frac { 1 }{ \sqrt { 35 } } ,\frac { 5 }{ \sqrt { 35 } } ,\frac { 3 }{ \sqrt { 35 } }
  • \frac { 1 }{ \sqrt { 35 } } ,\frac { 5 }{ \sqrt { 35 } } ,\frac { 3 }{ \sqrt { 35 } }
  • None of these
If from the point P ( f , g , h ) perpendiculars PL , PM be drawn to y z and zx planes then the equation to the plane OLM is -
  • \frac { x } { f } + \frac { y } { g } + \frac { z } { h } = 0
  • \frac { x } { f } + \frac { y } { g } - \frac { z } { h } = 0
  • - \frac { x } { f } + \frac { y } { g } + \frac { z } { h } = 0
  • \frac { x } { f } - \frac { y } { g } + \frac { z } { h } = 0
The equation of the plane passing through (1, 1, 1) and (1, -1, -1) and perpendicular to 2x - y + z + 5 = 0 is
  • 2x + 5y + z - 8 = 0
  • x + y - z - 1 = 0
  • 2x + 5y + z + 4 = 0
  • x - y + z - 1 = 0
The direction ratios of two lines are (4,3,5) and (\lambda, -1, 2). If the angle between them is 45^{o}, a value of \lambda is
  • 0
  • 2
  • 3
  • -1
The st lines whose direction cosines satisfy:
al+bm+cn=0 and fmn+gnl+hlm=0 are perpendicular if: 
  • \dfrac {f}{a}+\dfrac {g}{b}+\dfrac {h}{c}=0
  • \dfrac {a^{2}}{f}+\dfrac {b^{2}}{g}+\dfrac {c^{2}}{h}=0
  • \sqrt {af}+\sqrt {bg}+\sqrt {ch}=0
  • a^{2}f+b^{2}g+c^{2}h=0.
If l_1, m_1, n_1 and l_2, m_2, n_2 are the direction cosines of two perpendicular lines, then the direction cosine of the line which is perpendicular to both the lines , will be
  • (m_1n_2 - m_2n_1), (n_1l_2 - n_2l_1), (l_1m_2 - l_2m_1)
  • (l_1l_2 - m_1m_2), (m_1m_2 - n_1n_2), (n_1n_2 - l_1l_2)
  • \dfrac{1} {\sqrt {l^{2}_1+m^{2}_1+n^{2}_1}}, \dfrac{1} {\sqrt {l^{2}_2+m^{2}_2+n^{2}_2}}, \dfrac{1} {\sqrt3}
  • \dfrac{1} {\sqrt3}, \dfrac{1} {\sqrt3}, \dfrac{1} {\sqrt3}
If two straight lines having directions cosines \lambda, m, n and f, g, h satisfy \lambda+m+n=0 and fmn+gn\lambda+h\lambda m=0 and are perpendicular then f+g+h is equal to
  • 0
  • 1
  • -1
  • 2
The Dr's of two lines are 1, -2, -2 and 0, 2, 1 the Dc's of the line perpendicular to the above lines are :-
  • \frac { 2 }{ 3 } ,-\frac { 1 }{ 3 } ,\frac { 2 }{ 3 }
  • -\frac { 1 }{ 3 } ,\frac { 2 }{ 3 } ,\frac { 2 }{ 3 }
  • \frac { 1 }{ 14 } ,\frac { 3 }{ 4 } ,\frac { 2 }{ 3 }
  • None of these
In a plane there are 10 points, no three are in same straight line except 4 points which are collinear, then the number of straight lines are
  • 39
  • 41
  • 45
  • 40
The point collinder with (1,-2,-3) and (2,0,0) amoung the following is 
  • (0,4,6)
  • (0, -4, -5)
  • (0, -4, -6)
  • non of these
A line with direction ratio 2,7,-5 is drawn to intersect the lines \frac { x-y }{ 3 } =\frac { y-7 }{ -1 } =\frac { z+2 }{ 1 } and \frac { x+3 }{ -3 } =\frac { y-3 }{ 2 } =\frac { z-6 }{ 4 }  at P and Q respectively, then length of PQ is-
  • \sqrt { 78 }
  • \sqrt { 77 }
  • \sqrt { 54 }
  • \sqrt { 74 }
{ L }_{ 1 } and { L }_{ 2 } are two lines whose vector equations are { L }_{ 1 }:\vec { r } =\lambda \left[ \left( cos\theta +\sqrt { 3 }  \right) \hat { i } +\left( \sqrt { 2 } sin\theta  \right) \hat { j } +\left( cos\theta -\sqrt { 3 }  \right) \hat { k }  \right]
{ L }_{ 2 }:\vec { r } =\mu \left( a\hat { i } +b\hat { j } +c\hat { k }  \right) , where\lambda and \mu are scalars and\alpha is the acute angle between { L }_{ 1 }and{ L }_{ 2 } If the angle '\alpha ' is independent of \theta then the value of \alpha is
  • \dfrac { \pi }{ 6 }
  • \dfrac { \pi }{ 4 }
  • \dfrac { \pi }{ 3 }
  • \dfrac { \pi }{ 2 }
Direction ratio of two lines are l_{1}, m_{1},n_{1} and  l_{2},m_{2},n_{2} then direction ratios of the line perpendicular to both the lines are
  • l_{1}-l_{2}, m_{1}-m_{2}, n_{1}-n_{2}
  • l_{1}+l_{2}, m_{1}+m_{2}, n_{1}+n_{2}
  • m_{1}n_{2}-n_{1}m_{2}, n_{1}l_{2}-n_{2}l_{1}, l_{1}m_{2}-m_{1}l_{2}
  • m_{1}n_{2}-n_{1}m_{2}, n_{1}l_{2}-n_{1}l_{1}, l_{1}m_{2}-m_{1}l_{2}
The equation to the altitude of the triangle formed by (1, 1, 1), (1, 2, 3), (2, -1, 1) through (1, 1, 1).
  • \bar{r}=(\bar{i}+\bar{j}+\bar{k})+t(\bar{i}-3\bar{j}-2\bar{k})
  • \bar{r}=(\bar{i}+\bar{j}+\bar{k})+t(3\bar{i}+\bar{j}+2\bar{k})
  • \bar{r}=(\bar{i}+\bar{j}+\bar{k})+t(\bar{i}-\bar{j}+2\bar{k})
  • |\bar{r}|=5
The plane passing through (1, 1, 1), (1, -1, 1) and (-7, -3, -5) is parallel to 
  • X-axis.
  • Y-axis.
  • Z-axis.
  • None of these
Each group from the alternatives represents lengths of sides of a triangleStare which group does not represent a right-angled triangle.
  • ( 8,40,41 )
  • ( 20,25,30 )
  • ( 8,15,17 )
  • ( 6,8,10 )
there are 20 points in the plane on three of which are collinear. the number of straight lines by joining them is
  • 190
  • 200
  • 40
  • 500
The lines \vec{r}=i-j+\lambda(2i+k) and \vec{r}=(2i-j)+\mu(i+j-k) intersect for
  • \lambda=1, \mu =1
  • \lambda=2, \mu =1
  • All values of \lambda and \mu
  • No value of \lambda and \mu
The value of p so that the lines \frac { 1-x }{ 3 } =\frac { 7y-14 }{ 2p } =\frac { z-3 }{ 2 } and \frac { 7-7x }{ 3p } =\frac { y-5 }{ 1 } =\frac { 6-z }{ 5 } are at right angles are
  • 70/11
  • 7/11
  • 10/7
  • 17/11
What is the area of the triangle with vertices (0,2,2),\,(2,0,-1) and (3,4,0) ?
  • \frac{{15}}{2}sq unit
  • 15sq unit
  • \frac{{7}}{2}sq unit
  • 7sq unit
In the three points with position vectors (1, a. b) : (a, b, 3) are collinear in space, then the value of a + b is 
  • 3
  • 4
  • 5
  • none
The number of straight lines that can be drawn through any two points out of 10 points, of which 7 are collinear.
  • 25
  • 30
  • 35
  • 45
If the vectors 2\hat{i} + 3\hat{j} , ~5\hat{i} + 6\hat{j} , and 8\hat{i} +\lambda{\hat{j}} have their initial points at (1 , 1), then the value of \lambda so that the vectors terminate on one straight line is
  • 0
  • 3
  • 6
  • 9
If  ( 0,0 ) , ( a , 0 )  and  ( 0 , b )  are collinear, then
  • a b = 0
  • a = b
  • a = - b
  • a - b = c
If points (a - 2, a - 4); (a, a + 1) and (a + 4, 16) are collinear, then a is equal to
  • 5
  • -5
  • 7
  • -7
The direction cosines of the normal to the plane 2x - y + 2z = 3 are 
  • \dfrac{2}{3},\dfrac{-1}{3},\dfrac{2}{3}
  • \dfrac{-2}{3},\dfrac{1}{3},\dfrac{-2}{3}
  • \dfrac{2}{3},\dfrac{1}{3},\dfrac{2}{3}
  • \dfrac{2}{3},\dfrac{-1}{3},\dfrac{-2}{3}
The plane passing through the point \left ( 5,1,2 \right ) perpendicular to the line 2\left ( x - 2 \right ) = y - 4 = z - 5 will meet the line in the point
  • \left ( 1,2,3 \right )
  • \left ( 2,3,1 \right )
  • \left ( 1,3,2 \right )
  • \left ( 3,2,1 \right )
The equation of the plane passing through the points \left ( 3,2,-1 \right ), \left ( 3,4,2 \right ) and \left ( 7,0,6 \right ) is 5x + 3y - 2z =\lambda where \lambda is
  • 23
  • 21
  • 19
  • 27
The vector equation of line 2x - 1 = 3 y + 2 = z - 2 is 
  • \bar{r}=\left ( \dfrac{1}{2}\hat{i}-\dfrac{2}{3}\hat{j}+2\hat{k} \right )+\lambda \left ( 3\hat{i}+2\hat{j}+6\hat{k} \right )
  • \bar{r}=\hat{i}-> j+(2\hat{i}+\hat{j}+\hat{k})
  • \bar{r}=\left ( \dfrac{1}{2}\hat{i}-\hat{j}\right )+\lambda \left ( \hat{i}+2\hat{j}+6\hat{k} \right )
  • \bar{r}=\left ( \hat{i}+\hat{j} \right )+\lambda \left ( \hat{i}-2\hat{j}+6\hat{k} \right )
If P, Q  R are collinear points such that P( 7, 7) Q( 3, 4) and PR = 10 then R is 
  • (1, 1)
  • ( 1, -1)
  • ( -1, 1)
  • ( -1, -1)
0:0:1


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