Choose the correct answer from the given four options: If two sol… - Vidyadip

MCQ

Choose the correct answer from the given four options: If two solid hemispheres of same base radius $r$ are joined together along their bases, then curved surface area of this new solid is:

✓
$4\pi\text{r}^2$
B
$6\pi\text{r}^2$
C
$3\pi\text{r}^2$
D
$8\pi\text{r}^2$

✓

Answer

Correct option: A.

$4\pi\text{r}^2$

Because curved surface area of a hemisphere is $2 w^2$ and here, we join two solid hemispheres along their bases of radius $r$, from which we get a solid sphere.
Hence, the curved surface area of new solid $=2\pi\text{r}^2+2\pi\text{r}^2=4\pi\text{r}^2$

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