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What is the sum of the squares of direct...

What is the sum of the squares of direction cosines of the line joining the points (1,2,-3) and (-2,3,1)?

A

0

B

1

C

3

D

`2/sqrt26`

Text Solution

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The correct Answer is:
B
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DISHA PUBLICATION-THREE DIMENSIONAL GEOMETRY -Exercise -1 : Concept Builder (Topicwise)
  1. Find the angel between any two diagonals of a cube.

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  2. Three lines with direction ratios lt 1, 1,2 gtlt sqrt3-1 , -sqrt3-1,...

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  4. The distance between two points P and Q is d and the length of their p...

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  5. The projections of a directed line segment on the coordinate axes are ...

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  6. The projections of the segment PQ on the coordinate axes are -9,12,-8 ...

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  7. L1a n dL2 and two lines whose vector equations are L1: vec r=lambda((c...

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  8. If vecr=(hati+2hatj+3hatk)+lamda(hati-hatj+hatk) and vecr=(hati+2hatj+...

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  9. The lines (x-20/1=(y-3)/1=(z-4)/(-k and (x-10/k=(y-4)/2=(z-5)/1 are co...

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  10. A unit vector parallel to the straight line (x-2)/3 =(3+y)/(-1)=(z-2)/...

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  11. Find the equation of the two lines through the origin which intersects...

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  12. If the line through the points A (k,1,-1) and B(2k,0,2) is perpendicul...

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  13. The vector equation of the line (x-2)/(2)=(2y-5)/(-3),z=-1 is r=(2hati...

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  14. If P(3,2,-4),Q(5,4,-6) and R(9,8,-10) are collinear, then R divides PQ...

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  15. What is the value of n so that the angle between the lines having dire...

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  16. The equation of motion of rockets are x=2t, y=-4t, z=4t where the time...

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  17. The distance of point A(-2,3,1) from the line P Q through P(-3,5,2), w...

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  18. Distance of the point P(vecc) from the line vecr=veca+lamdavecb is

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  19. The length of the perpendicular drawn from the point (3,-1,11) to the...

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  20. The point of intersection of the lines ( x + 1 )/( 3 ) = ( ...

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