Stage: 5 Challenge Level: 
 |
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 $r$. |
Forces. Long problems. engineering. Complex numbers. Sine. Arcs, sectors and segments. Short problems. Pythagoras' theorem. Perimeters. Tangents.
Published June 1998.
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