How do you work out the radius or diameter of a circle?

Question

I'm honestly in desperate need for help, if you're not here to help, then **** off.

The circumference is 1000m, that's all I know.

Answer 1

Radius is 1/2 of diameter

Diameter is the circumference divided by Pi (3.14159265)

1000m = 3280.840/3.14159265 - 1044.3238' in diameter

Answer 2

Stuff you need to know (and probably do know, but let's make sure): Radius of circle, r, is distance from centre to circumference (i.e. to the actual circle). Diameter, d, is width of circle measured through the centre, i.e. twice the radius. Circumference of circle, c, is pi x diameter or 2 x pi x radius. (pi = 3.142 approx.) Arc is a portion of the circumference defined by the angle it makes at the centre. In other words, draw two lines from the centre to the circumference, a certain angle apart – the arc for that angle is the bit of circumference in between the lines. An arc that is the whole circumference has a measure of 360° because if you go around 360° you go around the whole circle. Now for the problems. (1) An arc with a measure of 60° is 60/360 of the whole circle, i.e. 1/6 of a circle. Now, because c = 2 x pi x r, c/6 = 1/3 x pi x r and if c/6 = 15 as stated then 15 = 1/3 x pi x r, so r = 15 / (pi/3) = 14.324 approx. (2) An arc with a measure of 270° is 270/360 of the whole circle, i.e. 3/4 of a circle. Now, because c = pi x d, (3/4)c = 3/4 x pi x d and if (3/4)c = 50 as stated then 50 = 3/4 x pi x d, so d = 50 / ((3/4)pi) = 21.221 approx.

Answer 3

There are lots of ways, but each method is dependent upon the needs and context of the problem. If you post more information, I can help you further.

**Edit** Since the circumference is 1000m, you just have to know the relationship between the circumference and the radius or diameter. The relationships are given by

C = 2*pi*r, or

C = pi*d.

Since C is 1000, you can plug this in and solve for the variable you want. Cheers!

P.S. I suspect that your textbook has this information already. If you read it and check the index, it can answer a lot of your questions.

Answer 4

You should post mor information about the problem, but I hope this helps...

radius(r)= 2 times the diameter(d)

If you have the circumfrence of a circle, then
C = 2(pi)r (pi is about 3.14)
r = circumfrence/(2 x 3.14)

If you have the area of a circle, then
A = (pi)r^2 (that means the radius is squared)
r= The squre root of (Area/3.14)

I hope this helps!

Just got the note: so use the formula
r = circumfrence/(2 x 3.14)
r = 1000m/(2 x 3.14)
r = 159.2356688m (round this to whatever you need to)
and the diameter is 2 times this amount

Answer 5

C=Pi * D. therefore D=C/Pi & R = C/2Pi where C = circumferance, Pi=22/7,D=Diameter & R=radius + good manners.

Answer 6

Radius is half the diameter.
If you know the circumference, radius is that divided by 2 times pi.
If you know the area, divide it by pi, then take the square root of whats left and that is the radius.

Answer 7

draw a circle. make a dot in the middle of the circle. measure one side of the circle from the middle to the end. it will give you the radius. then times the radius by 2. that will give you the diameter.

Answer 8

use this formulae

A=(pi)r^2 or

C=(pi)2r

where r is the radius, A is the area of the circle, and C is the circumference

Answer 9

What do you already know about the circle? Do you have its area, circumference, or some other piece of information?

Answer 10

If you know the circumference a good approximation is:

radius = circumference x 7/44
diameter = circumference x 7/22

If you know the area the approximation is

radius = sq. root (area x 7/22)

I hope this helps.
If you really want help you need to give us more info, you rude ungrateful person!.