From a parallelogram to a rectangle - Examples, Exercises and Solutions

Do you want to know how to prove that the parallelogram in front of you is actually a rectangle?
First, you should know that the formal definition of a rectangle is a parallelogram whose angle is $90^o$ degrees.
Additionally, if the diagonals in parallelograms are equal, it is a rectangle.

That is, if you are given a parallelogram, you can prove it is a rectangle using one of the following theorems:

• If a parallelogram has an angle of $90^o$ degrees, it is a rectangle.
• If the diagonals are equal in a parallelogram, it is a rectangle

We briefly remind you of the conditions for a parallelogram check:

1. If in a quadrilateral where each pair of opposite sides are also parallel to each other, the quadrilateral is a parallelogram.
2. If in a quadrilateral where each pair of opposite sides are also equal to each other, the quadrilateral is a parallelogram.
3. If a quadrilateral has a pair of opposite sides that are equal and parallel, the quadrilateral is a parallelogram.
4. If in a quadrilateral the diagonals cross each other, the quadrilateral is a parallelogram.
5. If a quadrilateral has two pairs of equal opposite angles, the quadrilateral is a parallelogram.