Measuremants .........

[rain]

Nah. Not that kind.

With all the brilliant minds posting here I know I will get a polite and proper answer. So, how do I measure the AREA of a circle when I know only the CIRCUMFERENCE?

And if you can tell me you may as well do the figuring too - the circle is 51 metres (167+ feet).

Ta-a-bit

[grabman]

rain

the Circumference is 2(pie)R or 2 times pie (22/7) times radius

the area is pie R squared or (22/7) times radius squared

so the radius = circumference /2 times Pie (22/7)
hope this makes sense!!

eg if Circ is 10 to calculate Radius it would be 10 divided by 2 times pie (22/7) ie
10/6.28571
R=1.59 approx

Geez, I know it works but it looks like sh!t, there must be an eassier way, just can't think at the moment!

Given the Circ is 51m I calculate the area to be approx 207m

Hope I'm right!

[rain]

Thanks, GM. I understand the explanation (of course the answer is in square metres), but it seems too big.
I'm trying to estimate the area of my back lawn which has no straight lengths.

[grabman]

rain imagine the circle has radius of 10m, the circ would be 62m approx using 2 times (22/7) times 10

the area would be 314m2 approx using (22/7) times 10 times 10

so yes it appears to big but seems to work!

happy gardening!

[Dogger Dan]

Just me but can't you do it this way

Circle Circumfernce = Pi*Diameter
51/3.14=Diameter
Dia=16.24 meters
r=8.12meters


Area= pi*r*r
=3.14*8.12meters*8.12meters
=207.03 square metres

really about 210 sq meters

I rounded on Pi and the radius a bit so you can give a bit more


Sorry Grab, I just like to keep the math easy.

Dogger

[grabman]

cheers Dogger,

similar result taking rounding into account!

I knew there was an easier way, just spent time using 2Pi *R with kids at school and didn't even look at Pi*D

[rain]

OK and thanks Fellas. I'll settle on approx 210m2 - if I over treat with feeding etc I can now blame somebody else.