• Rectangle – A parallelogram with four angles of equal size (right angles).
• Rhombus – A parallelogram with four sides of equal length. Any parallelogram that is neither a rectangle nor a rhombus was traditionall… See more

A simple (non-self-intersecting) quadrilateral is a parallelogram if and only if any one of the following statements is true:
• Two pairs of opposite sides are parallel (by definition).
• Two pairs of opposite sides are equal in len… See more

• Opposite sides of a parallelogram are parallel (by definition) and so will never intersect.
• The area of a parallelogram is twice the area of a triangle created by one of its diagonals.… See more

All of the area formulas for general convex quadrilaterals apply to parallelograms. Further formulas are specific to parallelograms:
A parallelogram with base b and height h can be divi… See more

To prove that the diagonals of a parallelogram bisect each other, we will use congruent triangles:
(alternate interior angles are equal in measure) (alternate interior angles are equal in me… See more