Proof: Converse of Parallel Lines 4
line ABCD
ECD = 140
ABF = 40
line BF
line CE
1.
1.
ABF = 40
ECD = 140
40
=
BCE
FBC =
FBC
FBC +
BCE =
FBC +
BCE
FBC and
BCE are supplementary
BCD =
BCE +
ECD
180
= 40
+
FBC
180
=
BCE + 140
line ABCD
140
=
FBC
FBC +
BCE = 140
+ 40
;
FBC +
BCE = 180
ABC = 180
BCD = 180
line BF
line CE
ABC =
ABF +
FBC
ProveIt!
by Michael Ferraro <
mferraro@balstaff.org
>.
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