Copyright © University of Cambridge. All rights reserved.
'Pencil Turning' printed from https://nrich.maths.org/
Show menu
Answer 1:1
C is $\frac13$ of the way along from $a$Semicircles with centre B have radius $2a$ and $3a$:
A moves total distance $3a\pi$
C moves distance $2a\pi+a\pi = 3a\pi$
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.