What is true of all parallelograms?

Answer 1

The definition of a parallelogram is that it's a quadrilateral in which both pairs of opposite sides are parallel. So, that part is true about all parallelograms. Apart from that, there are some other properties that can be deduced, such as:

* Opposite sides are congruent

* Opposite angles are congruent

* The diagonals bisect one another

* The sum of the squares of the sides equal the sum of the squares of the diagonals

As well as some other properties.