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By inscribing a circle in a square and then a square in a circle find an approximation to pi. By using a hexagon, can you improve on the approximation?

A Rolling Disc - Periodic Motion

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Belt

Age 16 to 18
Challenge Level

Diagram of problem A length of thin wire ($L$ ) binds together two cylindrical welding rods, whose radii are $R$ and $r$ , by passing all the way around them both.

Find $L$ in terms of $R$ and $r$.

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