Question

Triangle CDA is the image of triangle ABC after a 1800 rotation around the midpoint of segment AC. Triangle ECB is the image of triangle ABC after a 1800 rotation around the midpoint of segment BC.

Explain why ABCD and ABEC are parallelograms.
Identify at least two pairs of congruent angles in the figure and explain how you know they are congruent.
Explain how to use what you know about the sum of the angles in a triangle to figure out the sum of the angles of quadrilateral ABED.

Answer 1

1. they both have 2 different congruent sides

2. angles ACD and BEC, since they are the same triangles, and are at congruent ends

3. since they are all the same triangle and has just been rotated some, you can figure out that it is the same triangle. once you figure out the angles for one of the triangles, you can figure outit for the other 2 since they are all congruent.

i hope this helped :)