You are Here: Home >< Maths

# how to work out the area of a circle

Announcements Posted on
Last day to win £100 of Amazon vouchers - don't miss out! Take our quick survey to enter 24-10-2016
1. i need to know how to work out the area of a circle by using the diameter
so if the diameter was 12.3 what would be the answer and how would you work it out?
2. divide diameter by two to get the radius.

area = pi x radius squared
3. Have you learnt any formulas for finding the area of a circle?

4. right so just let me check ive done this question right and if i have im sorted
the question was find the area of a circle by using diameter=14.8cm
so i do 14.8 divided by 2=7.4 pie time 7.4 squared=172.3

is this correct?
5. 3.14*6.15 squared = 118.76 (2dp)

I think
6. It's 172.03, but I'm guessing that was just a typing error.
7. Right, this is a rhyme (!) which will mean u never 4get this formulae again!!!

Tweedle dum and tweedle dee,
round the circle is pie x d,
but if the area be declared,
the formula is pie x r squared!

Learn this and then use it. Obviously, d is diameter and r is radius!

Enjoy!
8. pie r squared where r is half the diameter
9. Sounds about right 2 me. Is this work 4 2morrow lol?
10. (Original post by Louismoore16)
right so just let me check ive done this question right and if i have im sorted
the question was find the area of a circle by using diameter=14.8cm
so i do 14.8 divided by 2=7.4 pie time 7.4 squared=172.3

is this correct?
You've changed the question slightly. In your first post, you said the diameter = 12.3

But anyway, if the diameter is 14.8cm, then the area is 172.0336... (not 172.3), but you'd probably want to round that down to 172cm squared.
11. ok thanks for all you help
L-C-17: this is for my maths homework lol
Tomthecool: i changed the question half way throught to 14.8 so i could check if i go it right
and IChem: yes i ment to put 172.03 but my key is abit sticky lol
and sorry about posting so much of the same thing, my page kept refreshing and sending.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: September 23, 2008
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams