Need some help with Geometry!

What does [AEB]  mean?   I have not seen that notation before.

These two triangles are similar.

Can you work out why.

Hint;   consider the three angles on each one.

Notice that AC and BD intersect each other at E 

So,

using our knowledge of V.O.A (Vertical opposite angles) 

We know that AEB = DEC (Angle) 

We already know AEB=50, therefore, CED=50 

With more proof, 

Since, m(B)=m(C)

since, AC intersect DB at point E

Therefore m(AEB)=M(DEC)=50

Therefore, M(EAB)=m(EDC)

We deduce that triangle AEB is similar to triangle DEC 

we can also deduce that EB/EC = ED/EA = AB/DC 

so 5/4=ED/EA =AB/DC 

My guess, Guests, and Melody, is that it's the area of the triangle.