Polygons are 2D closed shapes having straight sides. Although the smallest number of sides a polygon can have is 3; we will look at a polygons having 5 sides and more. Polygons can be of 2 types. Regular and Irregular.

Regular Polygons
Irregular Polygons

1. Sum of Interior Angles in a Polygon

Sum of all internal Angles = (n – 2) x 180

where n = number of sides of the polygon

5, 6, 7 and 8-sided polygons

2. Exterior Angle of a Polygon

Exterior Angle = 360/n

where n = number of sides of the polygon

Exterior Angle of a Pentagon

3. Interior Angle of a Polyon

Interior Angle = 180 – Exterior Angle

Interior Angle of a Pentagon
(R&F) Algebra - Expanding Brackets
Shapes - Circle