Answer with explanation:
Given: E is the mid point of DF.
Prove: 2 DE=D F
Proof with explanation:
It is given that
is mid point of
.
1.→
So,

-------------------------By Definition of mid point
2.→ DE=E F----------------Segment Congruence Postulate
3.→DE+E F=D F ----------------Segment Addition Postulate
4.→DE+DE=D F-------------By Substitution
5.→Simplifying gives
2 DE=D F