What is the missing reason for the 3rd step in the proof below? Given: AX || CY, BX || DY, AB || CD
A ABX - ACDY
Prove: Slope of AB - slope of CD
Statement
Reason
1. Given
1. AX ||DY, BX ||DY AB || CD
A ABD - A DBC
2 AX ВХ
GYDY
2. Definition of similar triangles: Corresponding
sides of similar triangles are proportional
3. AX. DY - BX. CY
3.
DY. ex: CY
1 AX
4 v - slope of cookie
slope of AB
4. Definition of slope
5. Slope of AB - slope of CD
5. Substitution