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QJEEM22Ma1105: JEE Main 2022 Mathematics - Class 12 JEEM22Ma1105 Solution: Let l 1 be the line in xy-plane with x and y intercepts and…

Let l1 be the line in xy-plane with x and y intercepts 18{1 \over 8} and 142{1 \over {4\sqrt 2 }} respectively, and l2 be the line in zx-plane with x and z intercepts −18- {1 \over 8} and −163- {1 \over {6\sqrt 3 }} respectively. If d is the shortest distance between the line l1 and l2, then d −- 2 is equal to _______________.

Step-by-Step Verified Solution

x−1818=y−142=z0             {{x - {1 \over 8}} \over {{1 \over 8}}} = {y \over { - {1 \over {4\sqrt 2 }}}} = {z \over 0}\,\,\,\,\,\,\,\,\,\,\,\,\, ______L1

or x−181=y−2=z0{{x - {1 \over 8}} \over 1} = {y \over { - \sqrt 2 }} = {z \over 0} ..... (i)

Equation of L2

x+18−63=y0=z8{{x + {1 \over 8}} \over { - 6\sqrt 3 }} = {y \over 0} = {z \over 8} ...... (ii)

d=∣(c→−a→) . (b→×d→)∣b→×d→∣∣d = \left| {{{(\overrightarrow c - \overrightarrow a )\,.\,(\overrightarrow b \times \overrightarrow d )} \over {\left| {\overrightarrow b \times \overrightarrow d } \right|}}} \right|

=(14i^) . (42i^+4j^+36k^)(42)2+42+(36)2= {{\left( {{1 \over 4}\widehat i} \right)\,.\,\left( {4\sqrt 2 \widehat i + 4\widehat j + 3\sqrt 6 \widehat k} \right)} \over {\sqrt {{{\left( {4\sqrt 2 } \right)}^2} + {4^2} + {{\left( {3\sqrt 6 } \right)}^2}} }}

=232+16+54=151= {{\sqrt 2 } \over {\sqrt {32 + 16 + 54} }} = {1 \over {\sqrt {51} }}

d−2=51{d^{ - 2}} = 51

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