Final answer:
The reason that can be used to fill in the numbered blank space is: ΔABC ~ ΔBED. By stating that ΔABC is similar to ΔBED and using the Side-Angle-Side Similarity Postulate, we can prove that the line segment DE is parallel to line segment AC.
Step-by-step explanation:
The reason that can be used to fill in the numbered blank space is:
- ΔABC ~ ΔBED
- Side-Angle-Side Similarity Postulate
By stating that ΔABC is similar to ΔBED and using the Side-Angle-Side Similarity Postulate, we can prove that the line segment DE is parallel to line segment AC. This is because the corresponding parts of similar triangles have congruent angles, and the converse of the corresponding angles postulate states that if two lines are cut by a transversal and the interior angles on the same side of the transversal are congruent, then the lines are parallel.