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
C and Ð
- 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
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.