Question

which concept is used to prove that the opposite sides of a parallelogram are congruent? congruent triangles similar triangles similar rectangles congruent rectangles

Explanation:

When proving that the opposite sides of a parallelogram are congruent, we draw a diagonal of the parallelogram. This diagonal divides the parallelogram into two congruent triangles. By using the properties of congruent triangles (such as SSS - Side - Side - Side, SAS - Side - Angle - Side, etc.), we can show that the corresponding sides (which are the opposite sides of the parallelogram) are congruent. Similar triangles or rectangles do not directly help in proving the congruence of the opposite sides of a parallelogram in the standard proof. Congruent rectangles are not relevant as we are dealing with a parallelogram (not necessarily a rectangle) and the proof is based on triangle congruence.

Answer:

congruent triangles