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:

  1. The sum of the interior angles of a convex polygon of n sides is (2n-4) right angles or (2n-4) \times 90^o .
  2. If there is a regular polygon of n sides (n \ge 3) , then each of its interior angle is equal to \frac{2n-4}{n} \times 90^o
  3. Each exterior angle of a regular polygon of n sides is equal to ( \frac{360}{n} )^o
  4. If each exterior angle of a regular polygon is x^o , then the number of sides in the polygon is \frac{360}{x} 
  5. As the number of sides of a regular polygon increase , the measure of each interior angle also increases.
  6. If the polygon has n sides, then the number of diagonals in \frac{n(n-3)}{2} .
  7. 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 360^o ).

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

Advertisements