# Surface Area of Hemisphere – Formula and Examples

Here you will learn what is the formula for surface area of hemisphere (total and curved surface area of hemisphere) with examples.

Let’s begin –

## What is Hemisphere ?

Let us take a solid sphere, and slice it exactly ‘through the middle’ with a plane that passes through its centre. It gets divided into two equal parts which is called a hemisphere. (Because ‘hemi’ means ‘half’)

## Formula for Surface Area of Hemisphere

#### (i) Curved Surface Area of Hemisphere

Curved Surface Area (CSA) = $$2\pi r^2$$

#### (ii) Total Surface Area of Hemisphere

Total Surface Area (TSA) = $$3\pi r^2$$

Example : Find (i) the curved surface area and (ii) the total surface area of a hemisphere of radius 21 cm.

Solution : Here, radius = 21 cm

(i) The curved surface area of a hemisphere of radius 21 cm would be

CSA = $$2\pi r^2$$ = $$2 \times {22\over 7} \times 21 \times 21$$ = 2772 $$cm^2$$

(ii) The total surface area of the hemisphere of radius 21 cm would be

TSA = $$3\pi r^2$$ = $$3 \times {22\over 7} \times 21 \times 21$$ = 4158 $$cm^2$$

Example : Find (i) the curved surface area and (ii) the total surface area of a hemisphere of diameter 70 cm.

Solution : Here, diameter = 70 cm $$\implies$$ radius r = 35 cm

(i) The curved surface area of a hemisphere of radius 35 cm would be

CSA = $$2\pi r^2$$ = $$2 \times {22\over 7} \times 35 \times 35$$ = 7700 $$cm^2$$

(ii) The total surface area of the hemisphere of radius 35 cm would be

TSA = $$3\pi r^2$$ = $$3 \times {22\over 7} \times 35 \times 35$$ = 11550 $$cm^2$$