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QJEEM24Mab66e: JEE Main 2024 Mathematics - Class 11 JEEM24Mab66e Solution: If the circles and intersect at exactly two distinct points, then

If the circles (x+1)2+(y+2)2=r2(x+1)^2+(y+2)^2=r^2 and x2+y2−4x−4y+4=0x^2+y^2-4 x-4 y+4=0 intersect at exactly two distinct points, then

Multiple Choice Options

  • A 12<r<7\frac{1}{2}<\mathrm{r}<7
  • B 3<r<73<\mathrm{r}<7
  • C 5<r<95<\mathrm{r}<9
  • D 0<r<70<\mathrm{r}<7

Step-by-Step Verified Solution

If two circles intersect at two distinct points

amp;⇒∣r1−r2∣lt;C1C2lt;r1+r2amp;∣r−2∣lt;9+16lt;r+2amp;∣r−2∣lt;5 and r+2gt;5amp;−5lt;r−2lt;5rgt;3 ......... 2\begin{aligned}&amp; \Rightarrow\left|\mathrm{r}_1-\mathrm{r}_2\right|&lt;\mathrm{C}_1 \mathrm{C}_2&lt;\mathrm{r}_1+\mathrm{r}_2 \\&amp; |\mathrm{r}-2|&lt;\sqrt{9+16}&lt;\mathrm{r}+2 \\&amp; |\mathrm{r}-2|&lt;5 \text { and } \mathrm{r}+2&gt;5 \\&amp; -5&lt;\mathrm{r}-2&lt;5 \quad \mathrm{r}&gt;3 ~\text{......... 2}\end{aligned}

-3&lt;\mathrm{r}&lt;7\quad .... (1)

From (1) and (2)

3&lt;\text { r }&lt;7

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