Check the picture below.
we know B is the midpoint of AC, and we know ED is 4 units, since AD is a total of 8, then AE must also be 4 units, meaning point E is the midpoint of AD.
since E is the midpoint of AD and B is the midpoint of AC, then EB is the midsegment of the triangle, and is parallel to the base DC.
∡ABE = 60°
∡AEB = 90°
