Find the surface area of a sphere of diameter 14 cm.

Given,

Diameter of sphere (d) = 14 cm

Radius of sphere (r) = $\dfrac{\text{Diameter}}{2} = \dfrac{14}{2}$ = 7 cm.

By formula,

Surface area of a sphere (A) = 4πr²

Substituting values we get :

$A = 4 \times \dfrac{22}{7} \times (7)^2 \\[1em] = 4 \times \dfrac{22}{7} \times 7 \times 7 \\[1em] = 4 \times 22 \times 7 \\[1em] = 616 \text{ cm}^2.$

Hence, the surface area of a sphere = 616 cm².