Question

if the radius of a sphere is doubled then what will happen to its surface area...

Answer 1

If the radius of a sphere is doubled then the surface area will increase four times.
Radius = r
Surface Area = 4*22/7*r*r.
Radius = 2r
Surface area = 4*22/7*2r*2r = 4*22/7*4*r*r = 4(4*22/7*r*r).

Answer 2

Surface area of sphere will increase 4 times.

Solution:

Given:  The radius of a sphere is doubled.

Radius is denoted as r.

Surface area of sphere $=4 \pi r^{2}$

If ‘radius’ is doubled, then the radius can be written as 2r.

Replacing 2r in the area of surface formula i.e. $4 \pi r^{2}$, we get

$4 \times \frac{22}{7} \times(2 r)^{2} \text { (whereas } \pi=\frac{22}{7} )$

$=4 \times \frac{22}{7} \times 4 r^{2}$

$=16 \pi r^{2}$

Hence, the surface area of sphere will increase 4 times if the radius of that sphere is doubled.