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Symmetric Angles
Age 14 to 16
ShortChallenge Level 
The diagram has rotational symmetry of order four about $D$.
If angle $ABC$ is $15^{\circ}$ and the area of $ABEF$ is $24$cm$^2$, what is the length of $CD$?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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