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The straight lines whose direction cosin...

The straight lines whose direction cosines are given by `al + bm + cn = 0`,` fmn + gnl +hlm=0` are perpendicular if

A

`(f)/(a)+(g)/(b)+(h)/(c )=1`

B

`(f)/(a)+(g)/(b)+(h)/(c )=-1`

C

`(f)/(a)+(g)/(b)+(h)/(c )=0`

D

`(a)/(f)+(b)/(g)+(c )/(h)=0`

Text Solution

Verified by Experts

The correct Answer is:
C
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NIKITA PUBLICATION-THREE DIMENSIONAL GEOMETRY -MULTIPLE CHOICE QUESTIONS
  1. If a line makes angles (alpha)/(2), (beta)/(2), (gamma)/(2) with co-o...

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  2. Two lines with direction cosines l(1),m(1),n(1) and l(2), m(2), n(2) a...

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  3. The straight lines whose direction cosines are given by al + bm + cn =...

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  4. If the line vec(OR) makes angles theta(1),theta(2),theta(3) with the ...

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  5. If the line passing through origin makes angles theta(1), theta(2), th...

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  6. If a variable line in two adjacent position has direction cosines l,m,...

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  7. A line makes angles alpha,beta,gammaand deltawith the diagonals of a...

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  8. Find the angle between any two diagonals of a cube.

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  9. A line makes an angle alpha, beta, gamma, delta with the four diagonal...

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  10. If the edges of a rectangular parallelepiped are a,b, c, prove that th...

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  11. If cos alpha=(sqrt(3))/(2), cos gamma=(-1)/(2), then the direction ang...

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  12. If a line makes angles of measure 45^(@) and 60^(@) with the positive ...

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  13. A line makes angles of measures (pi)/(6) and (pi)/(3) with X-and Z-axe...

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  14. If a line is inclined at 60^(@) and 30^(@) with the X-and Y-axes respe...

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  15. If a line makes angles of measure 60^(@) and 45^(@) with OX and OZ, th...

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  16. If a line which makes angle 60^(@) with Y and Z axes, then the angle w...

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  17. A line makes angles alpha, beta, gamma with X, Y, Z axes respectively....

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  18. A line makes angles alpha, beta, gamma with X, Y, Z axes respectively....

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  19. A line makes angles alpha,betaa n dgamma with the coordinate axes. If ...

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  20. If direction angles of a line are alpha, beta, gamma such that alpha+b...

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