- HubPages
*»* - Education and Science

# 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×r^{2}. (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.

Answer

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×r^{2}

A= π×4^{2}

A= 50.3... cm^{2}

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

50.3... ÷ 2 = 25.1 cm^{2} (1 d.p)

**Example 2**

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

Answer

To begin with first find the area of the circle by using A =
π×r^{2}.

A = π×r^{2}

A= π×7^{2}

A= 154.1... cm^{2}

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 cm^{2} (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×r^{2}/2. This will means less lines of working out.

## Comments

thanks broham

thank you so much, it helped me with my homework

Thank this really helped me on my math homework

Lovely jubbly thanks a bunch

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

THANKS SO MUCH NOW I CAN ANWSER THE QUESTION ON MY MATH TEST TOMORROW! EVERYBODY SAID IT WAS HARD!!!!!!!!! BUT ILL PRON=BABLY DO GOOD NOW !!!! THANKS A BUNCH!

fantastic that is absolutly nice thanks

Really good thank you so much I am so grateful

Thanks Very easy to understand. Awesome

Nice

I Like it

Guess what

Geometry is also cool

Even my dog understands this

Really helpful thnx!

See ya

thanx you really helped me ace my test

fantastic very useful thanks.

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

thank you, this really does help :D

this is very useful thants

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

thank you so much

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

this was really simple and easy to understand, thanks

20