Quadrilaterals – Definition – Properties

The word “quadrilateral” has two Latin words quadri, a variant of four and latus meaning is “side”.

                   What is a quadrilateral

A quadrilateral is a polygon, with four edges or sides and four vertex or corners.

Just like as a triangle is 3 sides polygon, a pentagon is a 5 sides polygon and so on.

In above figure, ABCD is a simple quadrilateral (polygon) of four sides, it’s four sides are AB, BC, CD, and DA.

    It’s four angles are ∠A, ∠B, ∠C and ∠D.

The total of all four interior angles of a quadrilateral, ∠A, ∠B, ∠C and ∠D is 360 degree.

             ∠A+ ∠B+ ∠C + ∠D = 360º

The quadrilateral ABCD has two diagonals AC and BD.

Convex quadrilateral

In below figure ABCD is a convex quadrilateral

In a convex quadrilateral

∠A < 180º

∠B < 180º

∠C < 180º

∠D < 180º

Concave quadrilateral

In below figure ABCD is concave quadrilateral

In a concave quadrilateral

∠D > 180º

Properties

1. One common property of all quadrilaterals is every quadrilateral has four angles four sides and four vertices.

2. The total of all interior angles of a quadrilateral is 360⁰.

There are kinds of quadrilaterals, based on the sides and angles.

1. Parallelogram

2. Trapezium

3. Rectangle

4. Rhombus

5. Square

6. kite

7. Isosceles Trapezium