We can define a quadrilateral in two ways:
- A quadrilateral is a closed-form that is obtained by joining four points which are non-collinear to any three points.
- A quadrilateral is a shape which is closed with four vertices and four sides.
We can say that there are four sides, four angles, and four vertices are in a quadrilateral.
Think of the following quadrilateral, for example:
A quadrilateral \(ABCD\) will have two diagonals: \(AD\) and \(BC\).
Quadrilateral specific properties are:
- They have \(4\) sides.
- They have \(4\) vertices.
- They have \(2\) diagonals.
- The sum of all interior angles is \(360°\).
We will study in detail about the other properties of various quadrilaterals in the next theory.