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If l,m,n are direction cosines of a line...

If l,m,n are direction cosines of a line , then vector `li +mj+nk` is a

A

null vector

B

unit vector

C

non-unit vector

D

bound vector

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The correct Answer is:
B
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MARVEL PUBLICATION-THREE DIMENSIONAL GEOMETRY-MULTIPLE CHOICE QUESTIONS
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  3. If l,m,n are direction cosines of a line , then vector li +mj+nk is a

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  4. If |bar(u)| = sqrt(3) and bar(u) is equally inclined to co - ordinate...

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  5. If |bar(u)|=2 and bar(u) makes angles of 60^(@) and 120^(@) with OX a...

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  6. If a line makes angles theta(1), theta(2), theta(3) with the coordinat...

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  7. Find the angle between the lines whose direction ratios are: 2,-3,4 ...

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  9. If direction ratios of two lines are 2,-6,-3 and 4,3,-1 then directi...

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  10. A line makes 45^(@) with OX and equal angles with OY and OZ .Then the ...

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  11. What is the angle between the two lines whose direction numbers are (s...

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  12. If the line of the vector bar (r ) = lambda I + 2j - k makes angles a...

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  13. The number of lines which are equally inclined to the axes is :

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  14. The projection of the line segment joining the points A(-1,0,3) and B(...

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  15. Direction Cosines of a normal to the XOY - plane are

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  16. If the direction cosines of a line are 1/c,1/c,1/c rthen (A) c.0 (B) 0...

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  17. A mirror and a source of light are situated at the origin O and at a...

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  18. The direction Cosines of two lines at right angles are l(1),m(1),n(1)a...

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  19. The graph of the equation x^2+y^2=0 in the three dimensional space is ...

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  20. If the line OP of length r makes an angle alpha with the X - axis , an...

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