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



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