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Hint: Curved Surface Area (CSA) of hemisphere$S = 2\pi {r^2}$

Surface area is Curved surface area.

Curved Surface Area (CSA) of a Hemisphere is given by the formula$S = 2\pi {r^2}$ …(1)

We have to express ‘r’ in terms of ‘S’. So, by rearranging equation (1), we get

$\begin{gathered}

S = 2\pi {r^2} \\

{r^2} = \dfrac{S}{{2\pi }} \\

r = \sqrt {\dfrac{S}{{2\pi }}} \\

\end{gathered} $

The required formula is $r = \sqrt {\dfrac{S}{{2\pi }}} $

Note: If ‘Total’ surface area is mentioned in the question, the formula will differ. Look for

small word changes in the questions which can make a big difference to the solution.

Surface area is Curved surface area.

Curved Surface Area (CSA) of a Hemisphere is given by the formula$S = 2\pi {r^2}$ …(1)

We have to express ‘r’ in terms of ‘S’. So, by rearranging equation (1), we get

$\begin{gathered}

S = 2\pi {r^2} \\

{r^2} = \dfrac{S}{{2\pi }} \\

r = \sqrt {\dfrac{S}{{2\pi }}} \\

\end{gathered} $

The required formula is $r = \sqrt {\dfrac{S}{{2\pi }}} $

Note: If ‘Total’ surface area is mentioned in the question, the formula will differ. Look for

small word changes in the questions which can make a big difference to the solution.