Proof: Converse of Parallel Lines 4     
line ABCD
ECD = 140
ABF = 40
line BF line CE
1. 
1. 
180 = 40 + FBC
40 = BCE
FBC + BCE = FBC + BCE
ABC = ABF + FBC
FBC = FBC
BCD = BCE + ECD
ECD = 140
FBC and BCE are supplementary
180 = BCE + 140
ABF = 40
line BF line CE
ABC = 180
BCD = 180
140 = FBC
FBC + BCE = 140 + 40; FBC + BCE = 180
line ABCD



ProveIt! by Michael Ferraro <mferraro@balstaff.org>.
Copyright ©2010. All rights reserved.