Mathematics · Circles

JEE Main 2026 — 2 April, Evening Shift — Question 32

Let a circle pass through the origin and its centre be the point of intersection of two mutually perpendicular lines x+(k−1)y+3=0\mathbf{x} + (\mathbf{k} - 1)\mathbf{y} + 3 = 0 and 2x+k2y−4=02\mathbf{x}+ \mathbf{k}^2\mathbf{y} - 4 = 0. If the line x−y+2=0\mathbf{x} - \mathbf{y} + 2 = 0 intersects the circle at the points A and B, then (AB)^2 is equal to :

  1. Option A:

    10

  2. Option B:

    27

  3. Option C:

    18

    Correct
  4. Option D:

    34

Answer: C

Step-by-step solution

x+(k−1)y+3=0x+(k-1) y+3=0 2x+k2y−4=02 \mathrm{x}+\mathrm{k}^{2} \mathrm{y}-4=0 (11−k)(2k2)=1\left(\frac{1}{1-\mathrm{k}}\right)\left(\frac{2}{\mathrm{k}^{2}}\right)=1 2=k2−k32=\mathrm{k}^{2}-\mathrm{k}^{3} k3−k2+2=0\mathrm{k}^{3}-\mathrm{k}^{2}+2=0 k=−1\mathrm{k}=-1 Solving : 2(x−2y+3)=02(\mathrm{x}-2 \mathrm{y}+3)=0 2x+y−4=02 \mathrm{x}+\mathrm{y}-4=0 −5y+10=0-5 \mathrm{y}+10=0 y=2\mathrm{y}=2 x=1\mathrm{x}=1 Centre (1,2)(1,2) r=5\mathrm{r}=\sqrt{5} So circle is (x−1)2+(y−2)2=5(x-1)^{2}+(y-2)^{2}=5 Chord x−y+2=0\mathrm{x}-\mathrm{y}+2=0 p=12\mathrm{p}=\frac{1}{\sqrt{2}} ℓ=5−12=32\ell=\sqrt{5-\frac{1}{2}}=\frac{3}{\sqrt{2}} AB=62∴AB2=18\mathrm{AB}=\frac{6}{\sqrt{2}} \therefore \mathrm{AB}^{2}=18

Solution figure

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Circles
Topic
Introduction to Circles
Let a circle pass through the origin and its centre be the point of… | JEE Main 2026 PYQ with Solution · DhiX AI