posted by fredrick .
given ABCD is an isoceles trapezoid with AD parallel to BC; DE=DC
prove ABED is a parallelogram
Where are points E and F?
ther is no e and f it a two column proof
1.AD parr.BC;DE=DC 1.given
2.AB=DC 2.def of isos trap
6.AB parr. DE 6.?
I should have just asked where point E is. There is no F mentioned; I was wring about that. The question makes sense if E lies along the extended line BCE
ABED is a parallelogram if BE = AD and is parallel to AD, AND if AB is parallel and equal to AB. That is what you have to prove.
Clearly CDE is an isosceles triangle appended to ABCD. Prove that the angle ADC is the same as DCE. This will prove that CE is an extension of BC.