diameter... junior high question?

If I have a rope that is 84 inches in lenght and I form it into a circle... what is the diameter??? also what if it's 42 inches???

I know... it's so easy but I forgot... musta slept thru that class...

Anonymous2007-03-20T18:44:50Z

Favorite Answer

its been over 20 years for me ! I forget...divide 84 by 3.14

Moo2007-03-21T01:46:12Z

well what uve done is basically made that 84 inch rope into a circle with a perimeter of 84 inches.
To find the diameter, ud have to work backwards using the perimeter of a circle formula
which i believe is Pi*Diameter
so....
84 = Pi*D
D=84/Pi

if its 42 inches then..
D=42/Pi

Bhajun Singh2007-03-21T01:46:54Z

1)
Well, you know the circumference of the circle - 84 inches!

C = 2(pi)r
84 = 2(pi)r
r = 13.369 (approx.

Now, you have the radius, just multiply by 2 to get the diameter.

Diameter = 26.738 (approx)


2)
Same concept applies.

42 = 2(pi)r
r = 6.685 (approx.)

Diameter = 13.139 (approx).

virtuous82007-03-21T01:45:46Z

circumference = 2 * pi * r
circumference / pi = 2 * r = diameter
circumference / diameter = pi
circumference / pi = diameter

M2007-03-21T01:43:33Z

the circumference of the circle is
C= π * d
so
d = C/π

If the rope is 84 inches long then
d = 84/π
d = 26.74 inches.

If the rope is 84 inches long then
d = 42/π
d = 13.37 inches.

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