diameter of a circle with a 3" circumference

[spudo]

i have a strip light and i want to know the diameter with out taking it of the celing...i know the circumference which is 3 inches but dont know how to get the distance from one side to the other...
so can some one work out the diameter
thanks in advance
glenn

[carrot99]

could you do it with a 3" piece of string? I'm sure there's an excellent formula involving pi etc. but can't remember it!

[cazzz1975]

divide it by 3.142

[spudo]

divide the circumfrence by pi

[cazzz1975]

yes

[kitesurfer]

perimeter=2 x pie x r

where r = radius = diameter/2

[Buenchico]

As Cazzz states, just divide by Pi. That gives an answer of 0.95" (to 2 d.p), which is slightly bigger than (15/16)" or slightly smaller than (31/32)", depending upon how your rule is calibrated.

Chris

[spudo]

so the diameter of this tume is 0.95 of an inch which is an inch to me which means the light is t8...finaly found out what type of light it is...thanks all

[eltelioni]

Of course, you cannot know the answer precisely because pi is an irrational number, so 3 divided by pi is also irrational.

[catmando]

2 x Pi x r = circumferance of a circle
Pi roughly equals 22/7 so:

3inches x 7 / (2 x 22) = radius

0.477 inches = radius

So diameter = 0.95 inches (approx)

Hope this helps

[heathfield]

Also, see here.

[factor-fiction]

10clarion street's formula is incorrect- I assume it's a typing error

[Rollo]

Why is is wrond? It looks right to me.

[Rollo]

Scru that. It is wrong.