Quadrilateral:
A quadrilateral is a simple closed figure formed by the four line segments such that no two line segments cross each other except at their end points.
Points to Remember:
 In the above figure, ABCD is the quadrilateral formed by the four bounding lines segments AB, BC, CD and DA.
 The four line segments are called its sides.
 Four points A, B, C and D are called its vertices.
 A quadrilateral has four angles. They are Ð A, Ð
B, Ð
C and Ð
D.
 The sides AB and CD are called the opposite sides, and the sides BC and AD are the other two opposite sides.
 The angles, Ð
A and Ð
C are called opposite angles. Similarly
Ð
B and Ð
D are also opposite angles.
 The points A and C are called the opposite vertices. Similarly the points B and D are the other pair of opposite vertices.
 The line segment joining any two opposite vertices is called a diagonal.
 There are two diagonals in a quadrilateral, that is AC and BD.
 A quadrilateral has four sides, four angles and two diagonals.
 The sum of the angles of a quadrilateral is 360°.
Directions: Read the above review points carefully and answer the following questions:
 Illustrate each of the above review points by drawing a quadrilateral.
 Explain the different properties of a quadrilateral, in your own words, with examples.
