This chapter is based on polygons. We had published lecture notes on Polygons for Class 8 students. It would be a good idea to revise the Class 8: Polygons – Lecture Notes.

Important points to remember:

- The sum of the interior angles of a convex polygon of sides is right angles or .
- If there is a regular polygon of sides , then each of its interior angle is equal to
- Each exterior angle of a regular polygon of sides is equal to
- If each exterior angle of a regular polygon is , then the number of sides in the polygon is
- As the number of sides of a regular polygon increase , the measure of each interior angle also increases.
- If the polygon has sides, then the number of diagonals in .
- The sum of all exterior angles formed by producing the sides of a convex polygon in the same order is equal to four right angles (or ).

All the problems related to Polygons can be solved using the above key formulas / points.