Question

If a figure consists of 4 sides that are all congruent, then it is a parallelogram. Figure ABCD is a parallelogram. Therefore, ABCD has 4 congruent sides.

Answer 1

A rhombus is a parallelogram with all four sides congruent to each other. A square is a parallelogram with four congruent sides and four right angles. In other words, a square is a rectangle and arhombus. To prove that a parallelogram is a rectangle, we need to prove that one of its interior angle is right.