## Elementary Geometry for College Students (7th Edition)

1. Given 2. The midpoint of a segment is equidistant from the two ends of the segment. 3. The sum of the two pieces ($\overline{DE}, \overline{EF}$) equals to $\overline{DF}$ 4. We can replace $\overline{EF}$ with $\overline{DE}$ because thy are egal. 5. DE + DE = $2\times DE$ 6. We divide the equality by 2 to prove the statement.