Medium MCQ +4 / -1 PYQ · JEE Mains 2020

Let P be a plane passing through the points (2, 1, 0), (4, 1, 1) and (5, 0, 1) and R be any point (2, 1, 6). Then the image of R in the plane P is :

  1. A (4, 3, 2)
  2. B (6, 5, - 2) Correct answer
  3. C (3, 4, -2)
  4. D (6, 5, 2)

Solution

Plane passing through (2, 1, 0), (4, 1, 1) and (5, 0, 1) is <br><br>$$\left| {\matrix{ {x - 2} &amp; {y - 1} &amp; {z - 0} \cr {4 - 2} &amp; {1 - 1} &amp; {1 - 0} \cr {5 - 2} &amp; {0 - 1} &amp; {1 - 0} \cr } } \right|$$ = 0 <br><br>$\Rightarrow$ x + y – 2z = 3 <br><br>$\therefore$ Image of R(2, 1, 6) in this plane is <br><br>$${{x - 2} \over 1} = {{y - 1} \over 1} = {{z - 6} \over { - 2}} = - 2{{\left( {2 + 1 - 12 - 3} \right)} \over {1 + 1 + 4}}$$ <br><br>$\therefore$ (x, y, z) = (6, 5, –2)

About this question

Subject: Mathematics · Chapter: Three Dimensional Geometry · Topic: Direction Cosines and Ratios

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