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# 3D Geometry - Spheres watch

When I draw it from above, with each of the inner circles touching the outer one, I get the length from the circumference to the centre to be 10[(2+rt3)/rt3]. However, I think this is a "chord" rather than a radius...(?) So I don't know what to do next.
2. bump
3. Physically, I can show you how to measure it. But with maths ... I must give it a shot lol
4. Ok, got it.
r = 10cm
R = r(2 + sqrt(3))
5. (Original post by BCHL85)
Ok, got it.
r = 10cm
R = r(2 + sqrt(3))
How???

Did you draw various cross-sections...?

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Updated: February 2, 2006
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