Answer:
4 cm
Step-by-step explanation:
The midpoint segment has length ...
... L = AB/2 + BC + CD/2 = 16 cm
The entire segment has length ...
... AD = AB + BC + CD = 28 cm
If we subtract AD from 2L, we have ...
... 2L - AD - 2L = 2(AB/2 +BC + CD/2) - (AB +BC +CD) = 2(16 cm) -28 cm = 4 cm
... AB +2BC + CD -AB -BC -CD = 4 cm . . . . remove parentheses
... BC = 4 cm . . . . simplify
