What is a quadrilateral?
A simple closed curve or a polygon formed by four line-segments is called a quadrilateral.
The four line-segments forming a quadrilateral are called its sides.
The symbol of a quadrilateral is □.
Each shape shown below is a quadrilateral.
(i) Shape (d) is a special type of quadrilateral. Its opposite sides are equal. Each angle of it is a right angle. Its name is rectangle.
(ii) The quadrilateral (e) is named as square. All the sides of it are of equal measure and each angle is a right angle.
(iii) Shape (f) is a quadrilateral having the special name parallelogram and with opposite sides equal and parallel.
(iv) Shape (g) is the shape of a rhombus whose all sides are equal.
(v) The quadrilateral (h) is the shape of a trapezium.
A polygon covers a plane space whose area may be calculated. The length of the covering sides is called its perimeter.
Related Concepts on Geometry - Simple Shapes & Circle