Let $A B C D$ and $A E F G$ be squares of side 4 and 2 units, respectively. The point $E$ is on the line…

Let $A B C D$ and $A E F G$ be squares of side 4 and 2 units, respectively. The point $E$ is on the line segment $\mathrm{AB}$ and the point $\mathrm{F}$ is on the diagonal $\mathrm{AC}$. Then the radius $\mathrm{r}$ of the circle passing through the point $\mathrm{F}$ and touching the line segments $\mathrm{BC}$ and $\mathrm{CD}$ satisfies:
  1. $r=0$
  2. $2 r^2-4 r+1=0$
  3. $2 r^2-8 r+7=0$
  4. $r^2-8 r+8=0$

Solution



$\begin{aligned} & \mathrm{OF}^2=\mathrm{r}^2 \\ & (2-r)^2+(2-r)^2=\mathrm{r}^2 \\ & \mathrm{r}^2-8 \mathrm{r}+8=0\end{aligned}$

Asked in: JEE Main 2024 (05 Apr Shift 2)

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