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Question: Answered & Verified by Expert
If the lines x-21=y-31=z-4-k and x-1k=y-42=z-51 are coplanar, then k can have
MathematicsThree Dimensional GeometryJEE MainJEE Main 2013 (07 Apr)
Options:
  • A exactly two values.
  • B exactly three values.
  • C any value.
  • D exactly one value.
Solution:
2721 Upvotes Verified Answer
The correct answer is: exactly two values.

For x-x1a1=y-y1b1=z-z1c1

and x-x2a2=y-y2b2=z-z2c2 to be coplanar if 

x2-x1y2-y1z2-z1a1b1c1a2b2c2=0


1-1-111-kk21=0k=0,  -3

Hence, there are exactly two values of k.

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