Base angles of isosceles trapezoid

[fellie]

How can I prove that the base angles of an isosceles trapezoid are equal? I have most of it, but can't quite get there. It's already an established fact...please help.

 

[stapel]

What is the definition you're given of an "isosceles" trapezoid? What have you done so far?

(Different geometry books can use slightly different definitions and/or a massively different ordering of theorems. If you list what you've got, that may give the tutors a big leg up on helping you figure out the solution.)

Thank you.

Eliz.

 

[Denis]

Easy enough; go here: http://www.math.psu.edu/geom/koltsova/section13.html

 

[fellie]

Very appropriate response/reply. Thank you!

Thanks for the solution. Nice webpage to be directed too...