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Rhombus Diagonal

Age 11 to 14 Short
Challenge Level

The diagram on the right shows a rhombus FGHI and an isosceles triangle FGJ in which GF = GJ. Angle FJI = 111 °.

What is the size of angle JFI?

If you liked this problem, here is an NRICH task that 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.