Quadrangle
   - Shape, which has 4 sides and 4 angle.
   - The sum of the measures of the interior angles of any quadrangle is 360 °.
                                      Thrapezium
      - Thrapezium has at least a pair of parallel sides.
      - Sum of thrapezium’s angles, lying at the same arm is equal to 180o.
      - Formula to calculate the area:
                P(ab)h
      P - area           2
      a - lenght of higher base
      b - lenght of lower base
      h - height
      - An isosceles thrapezium’s diagonals intersect at right angles.
              Parallelogram
   - Parallelogram is a thrapezium.
   - It has 2 pair of parallel sides.
   - His parallel sides have the same length.
   - His diagonal intersect in half of their length.
   - Formula to calculate the area:
     Pah
   P - area
   a - lenght of base
   h - height
                Rhomboid
  - Rhomboid has 2 pair sides of the same lenght.
  - Sides of the same length are in contact with.
  - Angles between sides of different length are the same.
  - Formula to calculate the area:
   Pef
        2
  P - area
  e - first diagonal
  f - second diagonal 
                Rhombus
   - The sum of two adjacent angles is equal to 180o.
   - The diagonals intersect at an right angle and divide          
   rhombus into four right-angled triangles.
   - His sides are the same.
   - Formula to calculate the area:
      Pef
   P - area
   e - first diagonal
   f - second diagonal