Consider the proof. 1
2
Statement
AB DE
41 and 23 are corresponding 4
2 and 24 are corresponding 25
21223 224
AABC-ADEC
2
Given: Segment AB is parallel to line DE.
AD BE
Prove:
DC
3
4
Reason
given
der of corresponding angles
corresponding sthm
AA Similantythm
definition of similar triangles
segment addition postulate
EC
3
4
5
6
7
substitution
A
8
6. AC-AD-DC
BC-BE EC
7
AD-DC BEEC
OCTEC
8 DC BE
DCDCEC
9 AD BE
DC+1-EC-1
10. AD BE
DC - EC
addition of fractions
D
1
9. Simplication of fractions
3
10. Subtraction property
C
4
What is the missing statement in Step 5?
2.
E
AC = BC
B
AC
DC
BC
EC
OAD = BE
AD
BE