MCQ
If two solid$-$hemispheres of same base radius $r$ are joined together along their bases, then curved surface area of this new solid is:
- A$6\pi\text{r}^2$
- B$8\pi\text{r}^2$
- C$3\pi\text{r}^2$
- ✓$4\pi\text{r}^2$
✓
Answer
Correct option: D.
$4\pi\text{r}^2$
Because curved surface area of a hemisphere is $2\pi\text{r}^2$ and here,
we join two solid hemisphere along their bases of radius $r,$ from which we get a solid sphere.
Hence, the curved surface area of new solid $=2\pi\text{r}^2+2\pi\text{r}^2=4\pi\text{r}^2$
we join two solid hemisphere 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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