A parallelogram is a four-sided plane or a quadrilateral with opposite sides as parallel and opposite angles as equal. In any parallelogram, the diagonals intersect each other in halves. Any side of a parallelogram can be a base. The altitude of a parallelogram is the perpendicular from the base to the opposite parallel side. Thus, the area of a parallelogram= length of the base *its altitude.

Some of the commonly known and special forms of the parallelogram are the rectangle, rhombus and the square. In a rectangle, two parallel opposite sides are perpendicular to each other. In a rhombus all four sides measure the same. The square is a parallelogram in which all the four sides are of the same length and the two pairs of parallel sides lying opposite to each other are also perpendicular to each other.

Some of the commonly known and special forms of the parallelogram are the rectangle, rhombus and the square. In a rectangle, two parallel opposite sides are perpendicular to each other. In a rhombus all four sides measure the same. The square is a parallelogram in which all the four sides are of the same length and the two pairs of parallel sides lying opposite to each other are also perpendicular to each other.