Proof: Converse of Parallel Lines 3     
line ABCD
ECD = 140
ABF = 40
line BF line CE
1. 
1. 
ABC = 180
180 = 40 + FBC
140 = FBC
ABF = 40
line ABCD
line BF line CE
ECD = 140
ABC = ABF + FBC



ProveIt! by Michael Ferraro <mferraro@balstaff.org>.
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