a.If DE is 4.3 cm, AC = ?BDZ43EGiven: ABC is a triangleAсD is the midpoint of ABE is the midpoint of BC

Okay, here we have this:
According to Triangle Midsegment Theorem
Considering that D is the midpoint of AB and E is the midpoint of BC, we obtain the following equation:
Segment AC=2(Segment DE)
Segment AC=2(4.3)
Segment AC=8.6