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The line rijkijkr→=2i^-3j^-k^+λ(i^-j^+2k^) lies in the plane rijkr→.(3i^+j^-k^)+2 = 0. - Mathematics

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Question

The line `vec"r" = 2hat"i" - 3hat"j" - hat"k" + lambda(hat"i" - hat"j" + 2hat"k")` lies in the plane `vec"r".(3hat"i" + hat"j" - hat"k") + 2` = 0.

Options

  • True

  • False

MCQ
True or False
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Solution

This statement is False.

Explanation:

Direction ratios of the line `(hat"i" - hat"j" + 2hat"k")`

Direction ratios of the normal to the plane are `(3hat"i" + hat"j" - hat"k")`

So `(hat"i" - hat"j" + 2hat"k").(3hat"i" + hat"j" - hat"k")` = 3 – 1 – 2 = 0

Therefore, the line is parallel to the plane.

 Now point through which the line is passing

`vec"a" = 2hat"i" - 3hat"j" - hat"k"`

If line lies in the plane then

`(2hat"i" - 3hat"j" - hat"k").(3hat"i" + hat"j" - hat"k") + 2` = 0

6 – 3 + 1 + 2 ≠ 0

So, the line does not lie in the plane.

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Chapter 11: Three Dimensional Geometry - Exercise [Page 239]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 11 Three Dimensional Geometry
Exercise | Q 46 | Page 239

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