# Ex.13.4 Q3 Surface Areas and Volumes Solution - NCERT Maths Class 9

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## Question

Find the total surface area of a hemisphere of radius \(10\rm\, cm.\) \((\rm{Use\;\pi = 3.14})\)

Video Solution

Surface-Areas-And-Volumes

Ex exercise-13-4 | Question 3

## Text Solution

**Reasoning:**

A hemisphere is half of a sphere having one circular surface at the top.

\(∴\) Total surface area of a hemisphere is the half area of sphere and the top circular \({\rm{area}} = 3\pi {r^2}\)

**What is known?**

Radius of the hemisphere.

**What is unknown?**

Total surface area of the hemisphere.

**Steps:**

Radius of the hemisphere\( (r) = 10 \rm\,cm\)

Total Surface area

\[\begin{align} &= 3\pi {r^2}\\&= 3 \times 3.14 \times 10 \times 10\\&= 942\,\,\rm{cm^2} \end{align}\]

**Answer:**

Total surface area of the hemisphere \( = 942\,\rm{cm^2} \)