Question
Find the radius of a sphere whose surface area is $154 \mathrm{~cm}^2$
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Answer
In the given problem, we have to find the radius of a sphere whose surface area is given.
Surface area of the sphere $(S)=154 \mathrm{~cm}^2$
Let the radius of the sphere be $rcm$
Now, we know that surface area of the sphere $=4 \pi \mathrm{r}^2$
So,
$154=4\left(\frac{22}{7}\right)(\mathrm{r})^2$
$\mathrm{r}^2=\frac{(154)(7)}{(4)(22)}$
$\mathrm{r}^2=12.25$
Further, solving for $r$
$\mathrm{r}=\sqrt{12.25}$
$\mathrm{r}=3.5$
Therefore, the radius of the given sphere is $3.5 \ cm .$
Surface area of the sphere $(S)=154 \mathrm{~cm}^2$
Let the radius of the sphere be $rcm$
Now, we know that surface area of the sphere $=4 \pi \mathrm{r}^2$
So,
$154=4\left(\frac{22}{7}\right)(\mathrm{r})^2$
$\mathrm{r}^2=\frac{(154)(7)}{(4)(22)}$
$\mathrm{r}^2=12.25$
Further, solving for $r$
$\mathrm{r}=\sqrt{12.25}$
$\mathrm{r}=3.5$
Therefore, the radius of the given sphere is $3.5 \ cm .$
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