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:
- ✓$4\pi\text{r}^2$
- 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 $2\pi\text{r}^2$ 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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