Question

If the radius of sphere is triller, the surface area will increase by a factor of ____.

Answer 1

Remember that the surface area of a sphere with radius r is given by the following formula:

`SA\text{ = 4}\pi\text{r}^2`

then, if the radius triples, that's a factor of 3. The square of 3 is 9, so if the radius triples the area is multiplied by 9.

Then the surface area will increase by a factor of 9.