Medium INTEGER +4 / -1 PYQ · JEE Mains 2021

Let Q be the foot of the perpendicular from the point P(7, $-$2, 13) on the plane containing the lines ${{x + 1} \over 6} = {{y - 1} \over 7} = {{z - 3} \over 8}$ and ${{x - 1} \over 3} = {{y - 2} \over 5} = {{z - 3} \over 7}$. Then (PQ)2, is equal to ___________.

Answer (integer) 96

Solution

Containing the line $$\left| {\matrix{ {x + 1} &amp; {y - 1} &amp; {z - 3} \cr 6 &amp; 7 &amp; 8 \cr 3 &amp; 5 &amp; 7 \cr } } \right| = 0$$<br><br>$9(x + 1) - 18(y - 1) + 9(z - 3) = 0$<br><br>$x - 2y + z = 0$<br><br>$PQ = \left| {{{7 + 4 + 13} \over {\sqrt 6 }}} \right| = 4\sqrt 6$<br><br>$P{Q^2} = 96$

About this question

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

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