Mathematics · Straight lines

JEE Main 2026 — 22 January, Evening Shift — Question 10

Let L be the line x+12=y+13=z+36\frac{\mathrm{x}+1}{2}=\frac{\mathrm{y}+1}{3}=\frac{\mathrm{z}+3}{6} and let S be the set of all points (a,b,c)(\mathrm{a}, \mathrm{b}, \mathrm{c}) on L , whose distance from the line x+12=y+13=z+90\frac{x+1}{2}=\frac{y+1}{3}=\frac{z+9}{0} along the line L is 7. Then ∑(a,b,c)∈S(a+b+c)\sum_{(\mathrm{a}, \mathrm{b}, \mathrm{c}) \in \mathrm{S}}(\mathrm{a}+\mathrm{b}+\mathrm{c}) is equal to :

  1. Option A:

    3434

    Correct
  2. Option B:

    2828

  3. Option C:

    4040

  4. Option D:

    66

Answer: A

Step-by-step solution

MM is the point of intersection of L1L_{1} & L2L_{2}

⇒2λ−1=2μ−1,3λ−1=3μ−1,6λ−3=9\Rightarrow 2 \lambda-1=2 \mu-1,3 \lambda-1=3 \mu-1,6 \lambda-3=9

⇒λ=2=μ\Rightarrow \lambda=2=\mu

⇒M(3,5,9)\Rightarrow \mathrm{M}(3,5,9)

Now let point P be (2 K−1,3 K−1,6 K−3)(2 \mathrm{~K}-1,3 \mathrm{~K}-1,6 \mathrm{~K}-3) on L2\mathrm{L}_{2}

such that PM=7\mathrm{PM}=7

⇒(2 K−4)2+(3 K−6)2+(6 K−12)2=7\Rightarrow \sqrt{(2 \mathrm{~K}-4)^{2}+(3 \mathrm{~K}-6)^{2}+(6 \mathrm{~K}-12)^{2}}=7

⇒49 K2+196−196 K=49\Rightarrow 49 \mathrm{~K}^{2}+196-196 \mathrm{~K}=49

⇒K2+4−4 K=1\Rightarrow \mathrm{K}^{2}+4-4 \mathrm{~K}=1

⇒K2−4 K+3=0\Rightarrow \mathrm{K}^{2}-4 \mathrm{~K}+3=0

⇒K=1,3\Rightarrow \mathrm{K}=1,3

So points P&Q\mathrm{P} \& \mathrm{Q} are (1,2,3)&(5,8,15)(1,2,3) \&(5,8,15)

So sum of all co-ordinates of P&Q=34\mathrm{P} \& \mathrm{Q}=34

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Straight lines
Topic
Various forms of lines
Let L be the line frac x +1 2 =frac y +1 3 =frac z +3 6 and let S be… | JEE Main 2026 PYQ with Solution · DhiX AI