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JEE Main 202329 JanuaryEvening Shift
Exam
JEE Main
Year
2023
Date
29 January
Shift
Evening Shift
Subject
Mathematics
Chapter
Three Dimensional Geometry

JEE Main 2023 · 29 January · Evening Shift · Mathematics · Three Dimensional Geometry

If the lines (x - 1)/(1) = (y - 2)/(2) = (z + 3)/(1) and (x -...

If the lines x−11=y−22=z+31\dfrac{x - 1}{1} = \dfrac{y - 2}{2} = \dfrac{z + 3}{1} and x−a2=y+23=z−31\dfrac{x - a}{2} = \dfrac{y + 2}{3} = \dfrac{z - 3}{1} intersects at the point PP, then the distance of the point PP from the plane z=az = a is :

Options

  1. A1616
  2. B2828
  3. C1010
  4. D2222

Correct answer

B. 2828

Step-by-step solution

Let

L1:x−11=y−22=z+31=λ{L}_{1}: \dfrac{x - 1}{1} = \dfrac{y - 2}{2} = \dfrac{z + 3}{1} = \lambda

Point on L1≡(λ+1,2λ+2,λ−3)</p><p>And,</p><p>{L}_{1} ≡ \left(\lambda + 1, 2\lambda + 2, \lambda - 3\right)</p><p>And,</p><p>{L}_{2}: x−a2=y+23=z−31=\dfrac{x - a}{2} = \dfrac{y + 2}{3} = \dfrac{z - 3}{1} =\mu</p><p>Pointon</p><p>Point on{L}_{2} ≡ \left(2\mu + a, 3\mu - 2, \mu + 3\right)</p><p>Forfinding</p><p>For findingP,wemusthave</p><p>, we must have</p><p>\lambda - 3 = \mu + 3 ⇒ \lambda = \mu + 6 . . . \left(i\right)

2λ+2=3μ−2⇒2λ=3μ−4...(ii)2\lambda + 2 = 3\mu - 2 ⇒ 2\lambda = 3\mu - 4 . . . \left(ii\right)

Solving \left(i\right) \text{and }\left(ii\right), we get</p><p>\lambda = 22andand\mu = 16</p><p>Therefore,</p><p></p><p>Therefore,</p><p>P ≡ \left(23, 46, 19\right)</p><p>And,</p><p></p><p>And,</p><p>2\mu + a = \lambda + 1</p><p></p><p>⇒ 32 + a = 22 + 1</p><p></p><p>⇒ a = - 9</p><p>Distanceofpoint</p><p>Distance of pointP\left(23, 46, 19\right) from the plane z+9=0z + 9 = 0 is

=∣19+902+02+12∣= \left|\dfrac{19 + 9}{\sqrt{{0}^{2} + {0}^{2} + {1}^{2}}}\right| = 28units</p>units</p>

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