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dont round the number please.
and what is the formula?
thankx

2007-08-28 22:43:30 · 10 answers · asked by sweetmango 2 in Science & Mathematics Mathematics

10 answers

First, let's relate Area and Perimeter.

The formula for area is

A = &pi r^2

The formula for perimeter is

P = 2 &pi r

In the second formula, let's isolate r

r = P/(2&pi)

Substitute this value into the first formula.

A = &pi r^2
A = &pi [P/(2&pi)]^2
A = &pi P^2 (1/[4 &pi^2] )

Which further simplifies as

A = (1/4) P^2 (&pi / &pi^2 )

And we get a cancellation

A = (1/4) P^2 (1/&pi)

And we know P = 1000, so

A = (1/4)(1000)^2 (1/&pi)
A = ( 1000000/4 ) (1/&pi)
A = 250000/&pi

2007-08-28 22:59:36 · answer #1 · answered by niki einstien 2 · 0 2

First, let's relate Area and Perimeter.

The formula for area is

A = &pi r^2

The formula for perimeter is

P = 2 &pi r

In the second formula, let's isolate r

r = P/(2&pi)

Substitute this value into the first formula.

A = &pi r^2
A = &pi [P/(2&pi)]^2
A = &pi P^2 (1/[4 &pi^2] )

Which further simplifies as

A = (1/4) P^2 (&pi / &pi^2 )

And we get a cancellation

A = (1/4) P^2 (1/&pi)

And we know P = 1000, so

A = (1/4)(1000)^2 (1/&pi)
A = ( 1000000/4 ) (1/&pi)
A = 250000/&pi

2007-08-28 22:54:54 · answer #2 · answered by Puggy 7 · 0 3

First, you must find their diameter (d) to get area of circle. You actually can use formula πd to find their diameter (d) OR 2πr to find their radius (r). But I used πd as my calculation to get diameter (d).

You can't say the outer line of circle, 'perimeter'. You should say 'circumferences' that only specialize for circle only.

Circumference of circle : πd
3.142 x d = 1000m
d = 1000 / 3.142
d = 318.27m

Area of circle : πr²
= 3.142 x (318.27m / 2)²
Hence πr² is the area of circle, divide 348.27m by 2 because radius (r) is 2 times less than diameter (d). 2r = d.
= 3.142 x (159.14²)m
= 3.142 x 25323.95m
= 79567.85m²

Use π : 22 / 7 OR 3.142

2007-08-28 22:54:43 · answer #3 · answered by Anonymous · 0 2

Perimeter
= 2 x pi x R
= 1000

Therefore, R
= 500/pi m

Area
= pi x R^2
= pi x (500/pi)^2
= 250000/pi m^2

2007-08-28 22:51:36 · answer #4 · answered by Bananaman 5 · 0 3

Area of the circle is
A = pi[perimeter/2pi]^2
= perimeter^2/4pi
= (1000m)^2/4pi
= 250000sqm/3.142
= 79567.1546785 sqm.

2007-08-28 22:57:18 · answer #5 · answered by sv 7 · 0 4

The perimeter is 2 x pye x radius
Area is pye x radius squared

therefore radius = 1000 divided by 2 x pye = 159.1 metres
therefore area = pye x 159.1 x 159.1 = 79,554.5457 square metres - roughly

2007-08-28 23:03:51 · answer #6 · answered by Anonymous · 0 4

79577.47 sq.m.

Perimeter is the circumference, so 2*PI*R = circumference, so R = 1000/ (2*PI) = 159.155.
Area = PI*R^2 = PI*25330.3 = 79577.47 sq.m.

2007-08-28 22:54:15 · answer #7 · answered by JJ 7 · 1 2

P=Pi*D; where: Pi=3.1416 , D=diameter, P=perimeter
1000=3.1416D; D=318.31m
Area of circle=Pi*Dsquared/4;
A=3.1416*(318.31)(318.31)/4
A=79,577.71 sqm

hope that solves it

2007-08-28 23:01:54 · answer #8 · answered by noldzki 5 · 0 3

Just work backwards

2007-08-29 00:08:33 · answer #9 · answered by Anonymous · 0 2

I think you mean circumference

C=2pir
r=C/2pi
r=1000m/(2*pi)

A=pi*r^2
A=3.142*(1000m/(2*pi))^2
A=79577.47155

2007-08-28 22:58:55 · answer #10 · answered by jackt673 2 · 0 4

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