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Maths Exercices
Regular polygon

Polígono regularA regular polygon is apolygon which is equiangular (all angles are congruent) and equilateral (all sides have the same length).


  • The sides are the straight line segments that make up the polygon.
  • The vertex is a corner of the polygon. In any polygon, the number of sides and vertices are always equal.
  • The center is the point inside a regular polygon that is equidistant from each vertex.
  • The apothem of a regular polygon is the line from the center to the midpoint of a side.
  • The radius is the distance from the center to any vertex.
  • By definition, all sides are the same length, so the perimeter is simply the length of a side times the number of sides.
Area of a regular polygon:

where P is the perimeter and a is the apothem

Sometimes you will find a similar formula:

where n is the number of sides, s is the length of the each side and a is the apothem.

Find the area of the regular polygon:

= = = 120 cm2

The lenght of the side of a pentagon is 8 units. The lenght of the apothem is 5.51. Find its area.