Question

What is the missing step in this proof? (See the entire proof.)
Given: ΔABC (view diagram )
Prove: A midsegment of ΔABC is parallel to a side of ΔABC.
Statement Reason
(Steps 1−5)
6. AC¯¯¯¯¯ ∣∣∣∣ DE¯¯¯¯¯ definition of parallel lines
7. Let F be the midpoint of AC¯¯¯¯¯. defining a midpoint
8. F=(x1+x32,y1+y32) definition of midpoint
9. slope of DF¯¯¯¯¯ = y1+y32−y1+y22x1+x32−x1+x22 = y3−y2x3−x2
slope of BC¯¯¯¯¯ = y3−y2x3−x2 definition of slope
10.
11. DF¯¯¯¯¯ ∣∣∣∣ BC¯¯¯¯¯ definition of parallel lines
12. Similarly, EF¯¯¯¯¯ is parallel to AB¯¯¯¯¯. step similar to steps 1−11