What is the missing step in this proof? (See the entire proof.) Statement: slope of DF¯¯¯¯¯ = slope of BC¯¯¯¯¯ Reason: definition of slope Statement: slope of DF¯¯¯¯¯ = slope of BC¯¯¯¯¯ Reason: Transitive Property of Equality Statement: DF = BC Reason: Corresponding sides of congruent triangles are congruent. Statement: ΔADF≅ΔABC Reason: ASA Done 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¯¯¯¯¯. steps similar to steps 1−11