### Theory:

The diameter of an orange is $$8 \ cm$$. Calculate the total surface area of the half orange.

Solution:

Diameter of an orange $$(d)$$ $$=$$ $$8 \ cm$$

Radius of an orange $$(r)$$ $$=$$ $\frac{r}{2}=\frac{8}{2}=4\phantom{\rule{0.147em}{0ex}}\mathit{cm}$

A half orange is in the shape of a hemisphere.

Total surface area of a hemisphere $$=$$ $$3 \pi r^2$$ sq. units

$$=$$ $3×\frac{22}{7}×{4}^{2}$

$$=$$ $3×\frac{22}{7}×16$

$$=$$ $$150.86$$

Total surface area of the half orange is $$150.86 \ cm^2$$.

Important!
The value of $$\pi$$ should be taken as $$\frac{22}{7}$$ unless its value shared in the problem.