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Question: Answered & Verified by Expert
A circle is drawn in a sector of a larger circle of radius $\mathrm{r}$, as shown in the adjacent figure. The smaller circle is tangent to the two bounding radii and the arc of the sector. The radius of the small circle is -
MathematicsCircleKVPYKVPY 2012 (SA)
Options:
  • A $\frac{\mathrm{r}}{2}$
  • B $\frac{\mathrm{r}}{3}$
  • C $\frac{2 \sqrt{3} \mathrm{r}}{5}$
  • D $\frac{\mathrm{r}}{\sqrt{2}}$
Solution:
2156 Upvotes Verified Answer
The correct answer is: $\frac{\mathrm{r}}{3}$


Say the radius of smaller circle is $\mathrm{x}$ Here $\mathrm{OP}=\mathrm{x} \operatorname{cosec} 30^{\circ}$
while $\mathrm{OQ}=\mathrm{r}=\mathrm{x}+\mathrm{x} \operatorname{cosec} 30^{\circ}$
$\mathrm{x}=\frac{\mathrm{r}}{3}$

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