Mathematics · 3D Geometry

JEE Main 2026 — 6 April, Evening Shift — Question 43

Let the image of the point P(0,-5,0) in the line x−12=y1=z+1−2\frac{x-1}{2} = \frac{y}{1} = \frac{z+1}{-2} be the point R and the image of the point Q(0,-1/2,0) in the line x−1−1=y+94=z+11\frac{x-1}{-1} = \frac{y+9}{4} = \frac{z+1}{1} be the point S. Then the square of the area of the parallelogram PQRS is ______.

Answer: 162

Numerical answer — enter this value.

Step-by-step solution

P(0,−5,0)\mathrm{P}(0,-5,0)

x−12=y1=z+1−2=k\frac{\mathrm{x}-1}{2}=\frac{\mathrm{y}}{1}=\frac{\mathrm{z}+1}{-2}=\mathrm{k}

Let R(x1,y1,z1)\mathrm{R}\left(\mathrm{x}_{1}, \mathrm{y}_{1}, \mathrm{z}_{1}\right) 2k+1,k,−2k−12 \mathrm{k}+1, \mathrm{k},-2 \mathrm{k}-1 (2k+1)(2)+(k+5)(1)+(−2k−1)(−2)=0(2 \mathrm{k}+1)(2)+(\mathrm{k}+5)(1)+(-2 \mathrm{k}-1)(-2)=0 ⇒9k+9=0⇒k=−1\Rightarrow 9 \mathrm{k}+9=0 \Rightarrow \mathrm{k}=-1 ∴M1⇒(−1,−1,1)\therefore \mathrm{M}_{1} \Rightarrow(-1,-1,1)

R⇒(−2,3,2)R \Rightarrow(-2,3,2)

Q(0, -1/2, 0) x−1−1=y+94=z+11=λ\frac{x-1}{-1}=\frac{y+9}{4}=\frac{z+1}{1}=\lambda (−λ+1,4λ−9,λ−1)(-\lambda+1,4 \lambda-9, \lambda-1) S(x2,y2,z2)\mathrm{S}\left(\mathrm{x}_{2}, \mathrm{y}_{2}, \mathrm{z}_{2}\right) (−λ+1)(−1)+(4λ−172)(4)+(λ−1)(1)=0(-\lambda+1)(-1)+\left(4 \lambda-\frac{17}{2}\right)(4)+(\lambda-1)(1)=0 ⇒18λ−36=0⇒λ=2\Rightarrow 18 \lambda-36=0 \Rightarrow \lambda=2 M2⇒(−1,−1,1)\mathrm{M}_{2} \Rightarrow(-1,-1,1) S⇒(−2,−3/2,2)\mathrm{S} \Rightarrow(-2,-3 / 2,2)

PR=4+64+4=72=62QS=4+1+4=9=3 Ar. =12⋅62⋅3=92( Ar. )2=(92)2=162 Sq.unit \begin{aligned} & \mathrm{PR}=\sqrt{4+64+4}=\sqrt{72}=6 \sqrt{2} \\& \mathrm{QS}=\sqrt{4+1+4}=\sqrt{9}=3 \\& \text { Ar. }=\frac{1}{2} \cdot 6 \sqrt{2} \cdot 3=9 \sqrt{2} \\& (\text { Ar. })^{2}=(9 \sqrt{2})^{2}=162 \text { Sq.unit } \end{aligned}

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
3D Geometry
Topic
Straight Lines in 3D Geometry