How do we use the properties of parallelogram

Parallelogram: A quadrilateral with two pairs of Parallel sides

Properties:

1. The opposite angel are congruent.
   
2. Consecutive angels are supplementary.
   
3.  Opposite sides are congruent.
   
4. Diagonals bisect each other.
   

Its never true that the diagonal always congruent

Its never true that the diagonal s are always perpendicular 

Its never true that the diagonal always bisects the angel

For more help check out that links below 

• https://www.youtube.com/watch?v=CbPrwNi2m_4
• https://www.youtube.com/watch?v=ioTBllxJ91s
• http://www.mathwarehouse.com/geometry/quadrilaterals/parallelograms/
• http://www.mathopenref.com/coordparallelogram.html