Questions: AE=EC and m angle BAC=m angle DFE. AC=24 and m angle DFE=126 degrees.
DF=[?]
Transcript text: $A E=E C$ and $m \angle B A C=m \angle D F E . A C=24$ and $m \angle D F E=126^{\circ}$.
\[
\mathrm{DF}=[?]
\]
Solution
Solution Steps
Step 1: Determine if DE is a midsegment
Since AE = EC, E is the midpoint of AC. Also, since the angle at A (BAC) is congruent to the angle at F (DFE), it means that DE is parallel to BC. If a line segment's endpoint bisects a triangle's side and is parallel to the triangle's third side, then it is a midsegment. Therefore, DE is a midsegment of triangle ABC.
Step 2: Relate the length of the midsegment to the third side
The midsegment of a triangle is half as long as the third side of the triangle. In this case, the length of DE is half of BC. DE = BC/2.
Step 3: Relate the length of DF to the length of DE
Since D and F are midpoints of AB and BC respectively, DF is a midsegment of triangle ABC. Therefore, DF is half the length of AC, which is given to be 24.