Geometry Practice Test 2

Area of circle (i) when r = 8 cm
= $\mathit{\pi }{\mathit{r}}_1^2$
= π64
= 64π
Area of circle (ii) is where r = 9 cm
= $\mathit{\pi }{\mathit{r}}_2^2$ = 81π
Area of path $\left({\mathit{r}}_2-{\mathit{r}}_1\right)$
= 81π − 64π = 17π

According to the given statement,
Area of circle (iii) = 81π +17π = 98π
Now area of the circle = $\mathit{\pi }{\mathit{r}}^2$
98π = $\mathit{\pi }{\mathit{r}}^2$
${\mathit{r}}^2$ = 98
r = $7\sqrt{2}$ cm