Question

Find the surface area of a sphere of radius 7cm.

Answer 1

In general if we have a sphere of radius R then surface area (S) can be calculated by formula as given below:
$S=4\pi {{R}^{2}}$
In formula $\pi $ is a constant and its value is $\dfrac{22}{7}$ or 3.14.

Complete step-by-step answer:
In given question radius of sphere is $R=7cm$
Surface area of sphere is
$\Rightarrow S=4\pi {{R}^{2}}$
$\Rightarrow S=4\times \dfrac{22}{7}\times {{(7)}^{2}}$
$\Rightarrow S=88\times 7$
$\Rightarrow S=616\,c{{m}^{2}}$
Hence the surface area of the given sphere is $616\,c{{m}^{2}}$.

Note: Whenever in our calculation if we have any multiple of 7 in the numerator then we always put $\pi =\dfrac{22}{7}$to make calculation easy and accurate. As in the given question we have a radius of 7 that’s why we use $\pi =\dfrac{22}{7}$. In general the surface area of a sphere is the amount of region covered by the surface of a sphere. Unit of surface area is in ${m}^{2}$ or ${cm}^{2}$ .