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Maths Problem

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I can't believe it's not better

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I've just started to make some progress on a painting I've been meaning to do for ages.

The painting is something like a mobile (the sort that hangs off a ceiling, and flaps about a bit in a breeze), with circles hanging from threads, like this dodgy sketch.

blog-4119-1148558681_thumb.jpg

The circles are to be thought of as 3d spheres and the idea is whether or not the eye can see if they balance out correctly (or not). I suspect not if it's subtle enough, but nevermind, who cares.

Already I've reached the first stumbling block - how to rearrange the formula for volume of a sphere to get the radius. ie, I want to specify a volume and find r. I've been looking around the internet for a simple fix but can't find anything.

V= 4/3.pi.r3

I know I should have really paid more attention in school and it's my own stupid fault, but if anyone can help, I'd be well pleased!

I'd also like to name the painting in a mathy way, describing the branches and spheres and their whereabouts, so that it could be reproduced from the name, if possible.

I hope you can understand what I'm blithering on about :rolleyes:

Please help!

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Tut tut see Maths was important :p

As for the formula it is

r = cube root of (0.75/pi * V)

(the cube root button on the calculator looks like the square root but with a little 3 to the left)

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Tut tut see Maths was important :p

As for the formula it is

r = cube root of (0.75/pi * V)

(the cube root button on the calculator looks like the square root but with a little 3 to the left)

Many thanks lizziek, you're a genial genius! I'll post a pic up when it's finished. :) Hopefully before the years out. :closedeyes:

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