Question

if the radius of a sphere is doubled then its surface area becomes​

Answer 1

Hello Mate,

Here is your answer,

Let's solve this problem by taking a simple example,

Let's Take Radius(1) = 7 cm

Let's Take Radius(2) = 7 x 2 = 14 cm

(double the Radius(1))

We Know surface area of circle =

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

Substituting R1, we get

$4 \times \pi \times 7 \\ \\ = 28\pi \: \: \: \: \: \: ......(1)$

Substituting R2, we get

$4 \times \pi \times 14 \\ \\ = 56\pi \: \: \: \: \: \: ......(2)$

Divide eq(2) with eq(1) we get,

$\frac{56\pi}{14\pi} \\ \\ = 4$

So, if Radius of a sphere is doubles, it's surface area becomes 4 times than previous.

Hope it helps:)