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11 answers

1. find the aquar root of 36 which is 6
2. multiply 6 by 2 which gives you 12
3. multiply 12 by pi which gives you 12 pi
simple isn't it?

2006-08-27 17:38:11 · answer #1 · answered by wormhole 2 · 0 0

Area of a circle = (pi)*r^2
Circumference = 2 (pi) *r
where r= the radius.


If the Area is 36 pi sq cm, the radius must be 6 cm--that is, the square root of (36*pi/pi)

Plugging 6 into the formula for circumference makes the circumference 12 pi.

2006-08-27 15:13:46 · answer #2 · answered by Opie 1 · 1 0

First, make a picture that shows the target; include the black and white areas.
Then find the whole circle's area:
A = Area of whole circle = r^2 * pi.
A = 18^2 * pi.
A = 324 pi.

Next, setup the formulas for the black and white areas.
B = Area of black circle = r^2 * pi.

C = Area of white circle = A - B
B = A - B
2B = A
2B = 324 pi
B = 162 pi
Pi r^2 = 162 pi
R^2 = 162
R^2 = sq. rt. 162
R = 12.727

To find the area,
R^2 * pi
= 12.727^2 * pi
= 162 pi
= 508.9392 sq. in.

A = 1017.8784
B = 508.9392
C = 508.9392
Therefore, B=C and B + C = A.

The inner circle is B, 508.9392 sq. in.

I honestly don't know nore do I understand but I do know that this is what I got when I searched the question on the internet!!
Good luck to the one who comes up with the honest answer!!

2006-08-27 15:12:23 · answer #3 · answered by vtlovie 4 · 0 2

1. Let the Circumference of a circle = P = 2 x pi x R
where R is radius.

2. Let the Area of circle = A = pi x R^2
then the R = Root {A/pi}

3. Now substitude 2 into 1 yields,
Circumference = P = 2 x pi x root{A/pi}

4. Plug in your figure,
A = 36pi

5. Ans. 12pi or 37.704cm

2006-08-27 15:37:18 · answer #4 · answered by Mr. Logic 3 · 0 0

A = pi R^2

36 = pi R^2

6 = R

Circumference = 2 pi R
C = 2*6 pi
C= 12 pi

2006-08-27 15:26:13 · answer #5 · answered by Anonymous · 0 0

Area equals Pi r squared
Area equals 36 Pi
Area equals 6 squared Pi
r = 6
circumference equals 2 pi r
C = 6 pi times 2
C = 12 pi

2006-08-27 15:17:48 · answer #6 · answered by Bob Y 1 · 0 0

Area equals pi * r^2, so you should be able to solve for r

Circumference = 2 pi r

Since you know r, you can calculate the circumference.

2006-08-27 15:14:56 · answer #7 · answered by Anonymous · 0 0

You were doing ok until the area problems come up. Area with DIA = 66 use 3.14 for pi Radius = 33 Radius^2 = 1089 Area = 3419.5........answer Area with DIA = 12 Radius = 6 Radius ^2 = 36 Area = 113.04........answer All others looked ok.

2016-03-26 22:21:48 · answer #8 · answered by Anonymous · 0 0

Area of a circle=pi*r*r
Area of a circle is 36 pi sq cm
=pi*6*6
Radius of a cicle=6cm.
Circumference of a circle=pi*D,Where D is a diameter.
=pi*(2*r)
=pi*(2*6)
Circumference of a circle=pi*12
Take pi=3.14,then
Circumference of a circle=3.14*12=37.68cm.

2006-08-28 05:00:46 · answer #9 · answered by Anonymous · 0 0

First find the radius of the circle using the formula A = pr^2 (p = pi), so r is the square root of A/p = 36/p.

Having found the radius r, the circum. is given by C = 2pr..

You can combine these:

C = 2pr = 2p [36/p]^{1/2}

2006-08-27 15:28:48 · answer #10 · answered by Anonymous · 0 0

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