

∠BCA = ∠DAC (alternate interior angles).∠BAC = ∠DCA ( alternate interior angles).In parallelogram ABCD, compare triangles ABC and CDA. To Prove: The opposite sides are equal, AB = CD and BC = AD. Theorem 1: In a Parallelogram the Opposite Sides are Equal. If one pair of opposite sides is equal and parallel in a quadrilateral then it is a parallelogram.The diagonals of a parallelogram bisect each other.The opposite angles of a parallelogram are equal.The opposite sides of a parallelogram are equal.Four important theorems related to the properties of a parallelogram are given below: Further, these theorems are also supportive of understanding the concepts in other quadrilaterals.

The properties relating to the sides and angles of a parallelogram can all be easily understood and applied to solve various problems. The theorems on properties of a parallelogram are helpful to define the rules for working across the problems on parallelograms. Now, let us expand our knowledge by learning about the properties of diagonals of parallelograms in the following section. The opposite sides of a rhombus are equal and parallel to each other.The sum of any two adjacent interior angles is 180°.The diagonals of a rhombus bisect each other at 90°.All sides of a rhombus are equal in length.Both the diagonals of a rectangle are of the same length.All four angles of a rectangle are equal and measure 90° each.The opposite sides of a rectangle are equal and parallel.The opposite sides of a square are equal and parallel to each other.Both the diagonals of a square have the same length.The diagonals of a square bisect its angles.All four angles are equal and of 90 degrees each.The three different parallelograms are square, rectangle, and rhombus which are different from each other because of their properties yet they all come under the category of parallelograms.

Observe the following figure to understand the properties of a parallelogram.Īll the above properties hold true for all types of parallelograms, but now let us also learn about the individual properties of some special parallelograms. The opposite sides of a parallelogram are equal and parallel to each other.
