Connecting AC and EF at point G, it is easy to know that G is the center line of EF.

From the topic, EC CF is 0.5, so EF is the root of 2.

Find that CG is the root of 4, and find that AG=AC-CG.

Eg = ef/2 = root number 2 of 4.

So tan < EAG=EG/AG

Calculate tan