Mathematics · Circles

JEE Main 2024 — 9 April, Shift 1 — Question 28

Let the centre of a circle, passing through the point (0,0),(1,0)(0,0),(1,0) and touching the circle x2+y2=9x^{2}+y^{2}=9, be (h,k)(h, k). Then for all possible values of the coordinates of the centre (h,k),4(h2+k2)(h, k), 4\left(h^{2}+k^{2}\right) is equal to \qquad

Answer: 9

Numerical answer — enter this value.

Step-by-step solution

figure

(x−h)2+(y−k)2=h2+k2(x-h)^{2}+(y-k)^{2}=h^{2}+k^{2}

x2+y2−2hx−2ky=0x^{2}+y^{2}-2 h x-2 k y=0

∵\because passes through (1,0)(1,0)

⇒1+0−2 h=0\Rightarrow 1+0-2 \mathrm{~h}=0

⇒h=1/2\Rightarrow \mathrm{h}=1 / 2

∵OC=OP2\because \mathrm{OC}=\frac{\mathrm{OP}}{2}

(12)2+k2=32\sqrt{\left(\frac{1}{2}\right)^{2}+\mathrm{k}^{2}}=\frac{3}{2}

14+k2=94\frac{1}{4}+\mathrm{k}^{2}=\frac{9}{4}

k2=2\mathrm{k}^{2}=2

k=±2\mathrm{k}= \pm \sqrt{2}

∴\therefore Possible coordinate of c(h,k)(12,2)(12,−2)\mathrm{c}(\mathrm{h}, \mathrm{k})\left(\frac{1}{2}, \sqrt{2}\right)\left(\frac{1}{2},-\sqrt{2}\right)

4( h2+k2)=4(14+2)=4(94)=94\left(\mathrm{~h}^{2}+\mathrm{k}^{2}\right)=4\left(\frac{1}{4}+2\right)=4\left(\frac{9}{4}\right)=9

Answer key and solution verified before publishing.

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Exam
JEE Main 2024
Subject
Mathematics
Chapter
Circles
Topic
System of Two Circles and Common Tangents
Let the centre of a circle, passing through the point (0,0),(1,0) and… | JEE Main 2024 PYQ with Solution · DhiX AI