If ED is the midsegment of triangle ABC, then that means that the points E and D are the midpoints of segments AC and AB since the midsegment is found by joining the midpoints of a triangle. Since E and D are midpoints then:
[tex]AE\cong EC[/tex]
Also, by the midsegments theorem we have:
[tex]ED=2BC[/tex]
Also, since segments ED and BC are parallel, that means that:
[tex]\angle ADE\cong\angle ABC[/tex]
