4th Class Mathematics Geometrical Figures Quadrilateral

   Quadrilateral

The geometrical figure having four sides are called quadrilateral. Look at the following figures:

Properties of Quadrilaterals 

• A quadrilateral has four sides.
• A quadrilateral has four vertices.
• A quadrilateral has four angles.
• Sum of all four angles of a quadrilateral is \[\text{36}0{}^\circ \]

• Sides of the quadrilateral ABCD are AB, BC, CD, and AD
• Vertexes of the quadrilateral ABCD are point A, point B, point C and point D
• Angles of the quadrilateral are\[\angle \text{ABC}\], \[\angle \text{BCD},\text{ }\angle \text{CDA},\]and\[\angle \text{DAB}\]
• Sum of all the four angles of the quadrilateral ABCD , \[\angle \text{A}+\angle \text{B}+\angle \text{C}+\angle \text{D}=\]\[\text{6}0{}^\circ +\text{12}0{}^\circ +\text{8}0{}^\circ +\text{1}00{}^\circ =\text{36}0{}^\circ \]  

Types of Quadrilateral

In this chapter we will study about two types of quadrilateral:

• Rectangle
• Square  

Rectangle

Rectangle is a quadrilateral in which (i) all angles are of\[\text{9}0{}^\circ \]and (ii) opposite sides are equal in length.

ABCD is a rectangle in which

(i) \[\angle \text{A}=\angle \text{B}=\angle \text{C}=\angle \text{D}=\text{9}0{}^\circ \]

(ii) AB = CD = 6 cm, and BC = AD = 4 cm.  

Square

Square is a quadrilateral whose (i) All angles are of\[\text{9}0{}^\circ \]and (ii) All sides are equal

ABCD is a rectangle in which (i) \[\angle \text{A}=\angle \text{B}=\angle \text{C}=\]\[\angle \text{D}=\text{9}0{}^\circ \](ii)\[\text{AB}=\text{BC}=\text{CD}\]\[=\text{DA}=\text{5 cm}\]