Posted by fredrick on Saturday, October 27, 2007 at 6:31pm.
finish proof
given ABCD is an isoceles trapezoid with AD parallel to BC; DE=DC
prove ABED is a parallelogram

geometry  drwls, Saturday, October 27, 2007 at 6:37pm
Where are points E and F?

geometry  fredrick, Saturday, October 27, 2007 at 6:46pm
ther is no e and f it a two column proof
statements reasons
1.AD parr.BC;DE=DC 1.given
2.AB=DC 2.def of isos trap
3.<B=<? 3.?
4.<DEC=? 4?
5.<DEC=<B 5.?
6.AB parr. DE 6.? 
geometry  drwls, Sunday, October 28, 2007 at 1:48am
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.