Classifying Polygons

A polygon is a closed plane figure formed by three or more line segments.
Triangles and quadrilaterals are examples of polygons

A regular polygon is a polygon in which all sides are congruent and all angles are congruent

Polygons are named by the number of their sides and angles.
A polygon with three sides is a triangle. A polygon with four sides is a quadrilateral. Polygons with five sides are pentagons, and so on

The sum of the interior angle measures in a triangle is 180°. A quadrilateral can be divided into two triangles, so the sum of the interior angle measures in a quadrilateral is 2 x 180° = 360°

In general, the number of triangles is always 2 fewer than the number of sides. If a polygon has ‘n’ sides, it can be divided into ‘n – 2’ triangles

For an ‘n’ sided polygon, the sum of the interior angle measures in a polygon is (n-2) x 180°

Measure of each angle = Sum of the interior angle measures / No. of angles in the polygon