# Area of a semicircle. Finding the area of semi circles.

## Area of a semicircle video

To find the area of a semicircle first you need to find the area of the whole circle and divide your answer by 2, as a semicircle takes up half the space of a circle.

To find the area of the circle use A=π×r2.  (A stands for the area of the circle, π is Pi and r is the radius of the circle).

Let’s take a look at an example.

Example 1

Find the area of this semicircle.

First find the area of the whole circle. Make sure that you use the radius of the circle (the distance halfway across the circle), this is 4 cm as the diameter is 8 cm (the distance all the way across the centre of the circle).

A = π×r2

A= π×42

A= 50.3... cm2

Now all you need to do is divide the answer by 2

50.3... ÷ 2 = 25.1 cm2 (1 d.p)

Example 2

A semicircular shaped doormat has a radius of 7cm. Calculate the area of the doormat.

To begin with first find the area of the circle by using A = π×r2.

A = π×r2

A= π×72

A= 154.1... cm2

Again, all you need to do now is to divide the area of the circle by 2.

Do this by 154.1 ÷ 2 = 77.1 cm2 (1 d.p)

Extra Tips

If you don’t have a scientific calculator then use Pi as 3.14 on your pocket calculator.

As you do more examples you might just want to use the formula A = π×r2/2. This will means less lines of working out.

## More by this Author

Yomama 3 years ago

thanks broham

travis 3 years ago

thank you so much, it helped me with my homework

andrea 3 years ago

Thank this really helped me on my math homework

Palm 4 years ago

Lovely jubbly thanks a bunch

Mikah 4 years ago

I still don't understand this I am only 10 but my teacher has said that this is a question that is going to appear in my exam I don't understand what all the tt things mean sorry

Amana 4 years ago

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Rizza 5 years ago

Thanks Very easy to understand. Awesome

Johnson 6 years ago

Nice

I Like it

Guess what

Geometry is also cool

Even my dog understands this

See ya

dd 6 years ago

thanx you really helped me ace my test

shaz 6 years ago

fantastic very useful thanks.

Soph 6 years ago

Thanks, this really helped me answer a question in an exam paper :)

(: 6 years ago

thank you, this really does help :D

catman3000 6 years ago from England, UK Author

maths teacher  6 years ago

this is very useful thants

:) 6 years ago

Thanks, ;) simple and easy to understand as always, just hope it comes up in my exam =(

koyasha bridges 6 years ago

thank you so much

marco  7 years ago

thx this was helpful as my mate gave me the wrong note i would of failed if it weren't for this website i love u moderator :P

niv 7 years ago

this was really simple and easy to understand, thanks

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