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

From the Parallelogram to the Rectangle

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 90o 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 90o 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.

Suggested Topics to Practice in Advance

  1. From a Quadrilateral to a Rectangle

Practice From a parallelogram to a rectangle

Exercise #1

AAABBBDDDCCC90°

The quadrilateral ABCD is a parallelogram.

B=90° ∢B=90°

Is it a rectangle?

Video Solution

Answer

Yes.

Exercise #2

AAABBBDDDCCC120°

Is this parallelogram a rectangle

Video Solution

Answer

No

Exercise #3

AAABBBDDDCCC45°45°

Is this parallelogram a rectangle?

Video Solution

Answer

Yes

Exercise #4

AAABBBDDDCCC

The quadrilateral ABCD is a parallelogram.

AD = CB

Is the parallelogram a rectangle?

Video Solution

Answer

Yes, a parallelogram with equal diagonals is a rectangle.

Exercise #5

Perhaps all parallelogram is also a rectangle?

Video Solution

Answer

No, a rectangle necessarily has angles of 90°.

Exercise #1

Side DA is equal to side DE.

Is the parallelogram a rectangle?

454545E1E1E1E2E2E2AAABBBCCCDDDEEE

Video Solution

Answer

Yes.

Exercise #2

Is the parallelogram below a rectangle?

989898AAABBBCCCDDD

Video Solution

Answer

No

Exercise #3

Is the parallelogram below a rectangle?

AAABBBCCCDDD2664

Video Solution

Answer

Yes

Exercise #4

Is the parallelogram below a rectangle?

AAABBBCCCDDD3392

Video Solution

Answer

No

Exercise #5

Given the following parallelogram:

AAABBBCCCDDD30°70°

Is it a rectangle?

Video Solution

Answer

No