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The length of each side of a quadrilateral ABCD is a whole number of centimetres. Given that AB=4 \; \text{cm}, BC = 5 \; \text{cm} and CD = 6 \; \text{cm}, what is the maximum possible length of the fourth side DA?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
As Long as Possible
Age 11 to 14
ShortChallenge Level 
The length of each side of a quadrilateral ABCD is a whole number of centimetres. Given that AB=4 \; \text{cm}, BC = 5 \; \text{cm} and CD = 6 \; \text{cm}, what is the maximum possible length of the fourth side DA?
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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