Quadrilaterals

Quadrilaterals

1. Trapezoid

   • Definition
     • A quadrilateral with only one pair of parallel sides.
       • Elements
         • A trapezoid is a quadrilateral with a pair of opposite sides parallels. It can have right angles (a right trapezoid) and can have congruent (isosceles) sides, but they are not required.
           • Properties
             • The legs are congruent by definition. The angles of the lower base are congruent. The angles of the top base are congruent.
               • Classification
                 • Right
                   • It has a pair of right angles.
                 • Isoceles
                   • It has equal length of non-parallel sides. In the image, sides, AD and BC are equal.
                 • Scalene
                   • It neither has equal angles nor has equal sides.

2. Trapezium

   • Definition
     • The trapezium is a quadrilateral with two parallel sides.

3. Pararellograms

   • Definiton
     • A four-sided plane rectilinear figure with opposite sides parallel.
       • Elements
         • Two pairs of opposite sides are parallel (by definition). Two pairs of opposite sides are equal in length. Two pairs of opposite angles are equal in measure.
           • Properties
             • Opposite angles are equal. Opposite sides are equal and parallel. Diagonals bisect each other. Sum of any two adjacent angles is 180°
               • Cllassification
                 • Rhombus
                   • in which all sides are equal.
                 • Rectangle
                   • in which all angles are right angles and the diagonals are equal.
                 • Square
                   • A parallelogram with all equal sides and all angles equal to 90 degrees. The diagonals of a square are also equal.