Theory:

The diameter of an orange is \(8 \ cm\). Calculate the total surface area of the half orange.
 
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Solution:
 
Diameter of an orange \((d)\) \(=\) \(8 \ cm\)
 
Radius of an orange \((r)\) \(=\) d2=82=4cm
 
A half orange is in the shape of a hemisphere.
 
Total surface area of a hemisphere \(=\) \(3 \pi r^2\) sq. units
 
\(=\) 3×227×42
 
\(=\) 3×227×16
 
\(=\) \(150.86\)
  
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 is shared in the problem.