A parallelogram is a quadrilateral with two pairs of parallel sides. The opposite or facing sides of a parallelogram are of equal length, and the opposite angles of a parallelogram are of equal measure.
The formula for the area of a parallelogram is the same as that for a rectangle’s:
To make sense of this fact, notice that, as depicted below, a parallelogram with base b and height h can be divided into a trapezoid and a right triangle and rearranged into a rectangle of equivalent area.
A parallelogram can be rearranged into a rectangle of the same area
You should know that the diagonals of a parallelogram bisect each other. For example, in this figure,
since ABCD is a parallelogram, we know that AE = EC and BE = ED, as is indicated by the single and double hash marks.
Angles of a Parallelogram: