Area of Regular Polygon - Definition, Formula and Examples

Area of Regular Polygon - Definition, Formula and Examples

Edited By Team Careers360 | Updated on Jul 02, 2025 05:32 PM IST

The space enclosed by a regular polygon's margin would be its area. In other terms, the region that a regular polygon encloses is its area. Typically, it is expressed in square units. Depending on the type of polygon—regular or irregular—different formulas can be used to calculate the area of the polygon.

This Story also Contains
  1. What Is A Polygon?
  2. The Formula For Calculating A Regular Polygon's Surface Area
  3. The Area Of A Regular Polygon With N Sides Formula
  4. A Regular Polygon's Area Inside A Circle
  5. Properties Of Polygon

What Is A Polygon?

A closed, two-dimensional shape composed of straight lines is known as a polygon in geometry. Each side must bisect exactly two other sides, but only at their ends. Polygons must have a common endpoint and noncollinear sides. We are aware that a triangle is a polygon with the least sides. Basically, the polygon can be categorized as either convex or concave and regular or irregular. Any polygon with equal sides and interior angles is said to be regular. The method used to determine the area of regular polygons is based on the corresponding formulas for each polygon. Remember that an n-gon is a polygon with n sides.

The Formula For Calculating A Regular Polygon's Surface Area

For some of the most popular polygons, the formulas for the area of regular polygons are as follows:

  • Area of an equilateral triangle = \frac{\sqrt{3}}{4}a^{2} 1707798999316

Here "a" denotes the triangle's equilateral triangle's side length.

  • Area of a Square = a^{2} 1707798999646

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Here "a" denotes the square's side length.

  • Regular Pentagon’s Area = \frac{1}{4}\sqrt{[5(5+2\sqrt{5}]}a^{2} 1707798999086

Here "a" is the pentagon's side length.

  • Regular Hexagon’s Area = \frac{3\sqrt{3}}{2}a^{2} 1707798999525

Here "a" denotes the hexagon's side length.

The Area Of A Regular Polygon With N Sides Formula

When a polygon has "n" sides, the following formula can be used to determine its area:

The formula for Area of Regular Polygons = \frac{l^{2}n}{4\tan\frac{180}{n}} 1707798999376

Here "l" denotes the polygon's side length.

A Regular Polygon's Area Inside A Circle

According to the following formula, the area of a regular polygon encircled by a circle is:

Area of a regular polygon encircled by a circle = \frac{nr^{2}}{2}\sin\frac{2\pi}{n} 1707798999200

Here "n" denotes the number of sides and “r” denotes the circumradius.

Properties Of Polygon

  • Finding an apothem allows one to determine the area of a regular polygon given the length of one side.

  • Apothem divides a side into two equal portions by falling at a right angle on its center.

  • A square is a regular polygon with four sides, whereas an equilateral triangle has three sides. They are not prefixed as regular before the form name as a result.

  • The total interior angle of an n-sided polygon is (n-2)\times180^{o} 1707798999026

  • An n-sided regular polygon's inner angles are measured in terms of angles as: (n-2)\times\frac{180}{n} 1707798998967

  • Each exterior angle of an n-sided regular polygon's angle measures \frac{360^{o}}{n} 1707798998880

  • The number of diagonals in an n-sided polygon = \frac{n(n-3)}{2} 1707798999701

  • The number of triangles generated when a polygon's diagonals are connected from one corner = n-2

Frequently Asked Questions (FAQs)

1. What is a regular polygon? Give a few examples.

Any polygon with equal sides and interior angles is said to be regular. Examples of regular polygons: Equilateral Triangles, squares, regular pentagons, and regular hexagons.

2. Write down the formula to compute the area of a regular pentagon and a regular hexagon.

Regular Pentagon’s Area = \frac{1}{4}\sqrt{[5(5+2\sqrt{5}]}a^{2}   

Here "a" is the pentagon's side length.

Regular Hexagon’s Area = \frac{3\sqrt{3}}{2}a^{2}   

Here "a" denotes the hexagon's side length.

3. How to determine the area of a regular polygon with N Sides?

When a polygon has "n" sides, the following formula can be used to determine its area:

The formula for Area of Regular Polygons = \frac{l^{2}n}{4\tan\frac{180}{n}}   

Here "l" denotes the polygon's side length.

4. How to compute the area of a regular polygon inscribed in a circle.

According to the following formula, the area of a regular polygon encircled by a circle is:

Area of a regular polygon encircled by a circle = \frac{nr^{2}}{2}\sin\frac{2\pi}{n}  

Here "n" denotes the number of sides and “r” denotes the circumradius.

5. How many diagonals an n-sided polygon has?

The number of diagonals in an n-sided polygon = \frac{n(n-3)}{2}  

6. How does the area of a regular polygon relate to the concept of integration?
The area of a regular polygon can be calculated using integration by dividing the polygon into congruent triangles and summing their areas. As the number of sides increases, this method approaches the integral of a circle's area.
7. How does the area of a regular polygon change as the number of sides increases?
As the number of sides in a regular polygon increases, its shape becomes more circular, and its area approaches that of a circle. This concept is crucial in understanding the limit of polygon areas and its connection to circular area.
8. What's the connection between the area of a regular polygon and the area of a circle?
As the number of sides in a regular polygon approaches infinity, its area converges to that of a circle. This relationship is fundamental in calculus and demonstrates how integration can be used to calculate circular areas.
9. How does the area formula for a regular polygon relate to the concept of limits?
The area formula for a regular polygon involves the limit concept as the number of sides approaches infinity. This limit process transforms the polygon formula into the circle area formula, demonstrating a key application of calculus.
10. What role does the center of the polygon play in area calculations?
The center of the polygon is a key point in area calculations. It forms the vertex of the congruent triangles used to derive the area formula and is the endpoint of the apothem, which is used in alternative area formulas.
11. How does the area formula for regular polygons relate to the concept of regular tessellations?
Regular tessellations (patterns that fill a plane with no gaps or overlaps) are only possible with certain regular polygons. Understanding the area formula helps in calculating the coverage of these tessellations and their efficiency in filling space.
12. What's the relationship between the interior angles of a regular polygon and its area?
While the interior angles don't directly appear in the area formula, they're related to the number of sides, which is a key component of the formula. As the number of sides increases, the interior angles approach 180°, and the polygon's area approaches that of a circle.
13. How does the area of a regular polygon change if you double the side length?
If you double the side length of a regular polygon, its area increases by a factor of 4. This is because the area is proportional to the square of the side length, demonstrating a quadratic relationship.
14. Why does the area of a regular polygon increase more slowly than its perimeter as the number of sides increases?
As the number of sides increases, the polygon becomes more circular. The perimeter approaches the circumference of a circle linearly, while the area approaches the area of a circle quadratically, resulting in a slower rate of increase for the area.
15. How does the concept of inscribed and circumscribed circles relate to the area of regular polygons?
The radii of inscribed and circumscribed circles are closely related to the apothem and side length of the polygon. These relationships are crucial in deriving and understanding various forms of the area formula for regular polygons.
16. What is the general formula for the area of a regular polygon?
The area of a regular polygon with n sides, each of length s, is given by: A = (n * s^2) / (4 * tan(π/n)). This formula combines trigonometry and algebra to calculate the total area.
17. How is the apothem used in calculating the area of a regular polygon?
The apothem, which is the perpendicular distance from the center to any side, is used in the formula: Area = (1/2) * perimeter * apothem. This formula highlights the relationship between the polygon's sides and its center.
18. Why is the tangent function used in the area formula for regular polygons?
The tangent function in the formula (A = (n * s^2) / (4 * tan(π/n))) accounts for the angle between the sides of the polygon. It helps calculate the height of the triangles formed within the polygon, which is crucial for determining the area.
19. Why can't we simply multiply the number of sides by the area of one triangle to find the polygon's area?
While this approach seems intuitive, it's not accurate because the triangles formed within a regular polygon are not right triangles. The formula accounts for the angle between sides, which affects the height and thus the area of each triangle.
20. Can the area of any polygon be calculated using the regular polygon formula?
No, the regular polygon formula only applies to polygons with equal side lengths and equal interior angles. For irregular polygons, different methods like triangulation or the shoelace formula must be used.
21. How is the concept of symmetry important in deriving the area formula for regular polygons?
Symmetry is crucial because it allows us to divide the polygon into congruent triangles. This symmetry simplifies the calculation by letting us focus on one triangle and then multiply by the number of sides.
22. Why is it often easier to use the apothem in area calculations rather than the radius of the circumscribed circle?
The apothem forms a right triangle with half of a side of the polygon, making calculations more straightforward. The radius of the circumscribed circle, while related, doesn't form such a convenient right triangle for area calculations.
23. What's the significance of the factor 4 in the denominator of the area formula (A = (n * s^2) / (4 * tan(π/n)))?
The factor 4 in the denominator comes from the fact that we're dealing with half angles and half sides when breaking the polygon into triangles. It's a result of trigonometric identities used in deriving the formula.
24. Why isn't there a simple polynomial formula for the area of all regular polygons?
The area of a regular polygon involves trigonometric functions due to the angular relationships between sides. These transcendental functions can't be expressed as simple polynomials, which is why the formula includes the tangent function.
25. How can integration be used to verify the area formula for regular polygons?
Integration can be used by considering the polygon as a collection of infinitesimally small triangles. By integrating the areas of these triangles around the center, we can derive the same formula, providing a calculus-based verification of the algebraic formula.
26. What is a regular polygon?
A regular polygon is a closed shape with all sides of equal length and all interior angles of equal measure. Examples include equilateral triangles, squares, and regular pentagons.
27. How does the concept of regular polygons extend to three dimensions?
In three dimensions, regular polygons extend to regular polyhedra, such as Platonic solids. The principles of symmetry and regularity used in polygon area calculations extend to surface area and volume calculations in these 3D shapes.
28. How does the concept of regular polygons relate to the study of fractals?
Regular polygons serve as basic shapes in many fractal patterns. Understanding their areas is crucial in calculating fractal dimensions and in studying how these patterns fill space as they iterate, connecting geometry to complex systems theory.
29. What's the significance of the fact that only certain regular polygons can be constructed with compass and straightedge?
The constructibility of regular polygons relates to algebraic number theory. It highlights the deep connections between geometry and algebra, and has implications for understanding the areas of these polygons in terms of algebraic expressions.
30. How does the concept of regular polygons extend to non-Euclidean geometries?
In non-Euclidean geometries like spherical or hyperbolic geometry, regular polygons still exist but have different properties. Their areas are calculated differently, providing insights into how geometric concepts change in various spatial frameworks.
31. How does the area of a regular polygon compare to the area of its circumscribed circle?
The area of a regular polygon is always less than the area of its circumscribed circle. The ratio of these areas approaches 1 as the number of sides increases, which is a fundamental concept in the study of limits and integration.
32. How does the area of a regular polygon relate to its internal diagonals?
The diagonals of a regular polygon divide it into triangles. While not directly used in the standard area formula, understanding these diagonals can provide alternative methods for area calculation and help visualize the polygon's internal structure.
33. What's the connection between the area of a regular polygon and the concept of pi (π)?
Pi appears in the area formula for regular polygons (A = (n * s^2) / (4 * tan(π/n))) because of the circular nature of polygon arrangement. As the number of sides increases, the polygon approximates a circle, directly linking to the definition of pi.
34. How does the area of a regular polygon change if you increase the number of sides while keeping the perimeter constant?
If you increase the number of sides while keeping the perimeter constant, the area of the polygon increases. This is because the shape becomes more circular, enclosing more area with the same perimeter length.
35. Why is the area of a regular polygon always less than the area of its circumscribed circle?
The regular polygon fits inside its circumscribed circle, leaving small gaps near the vertices. These gaps account for the difference in area. As the number of sides increases, these gaps become smaller, but the polygon area always remains less than the circle area.
36. How can the area formula for regular polygons be used to approximate the area of irregular shapes?
Irregular shapes can be approximated by inscribing or circumscribing them with regular polygons. By increasing the number of sides, we can get increasingly accurate approximations of the irregular shape's area, a concept fundamental to integral calculus.
37. What's the relationship between the area of a regular polygon and its central angle?
The central angle of a regular n-gon is 360°/n. This angle is crucial in deriving the area formula, as it determines the shape of the triangles used in the calculation. The smaller this angle, the closer the polygon's area is to that of a circle.
38. Why is the area of a regular polygon always rational if its side length is rational, but this isn't true for circles?
The area formula for regular polygons involves only algebraic operations on the side length, ensuring that rational side lengths lead to rational areas. Circles, however, involve π in their area formula, which is transcendental, leading to irrational areas for rational radii.
39. How does the area of a regular polygon relate to its inscribed circle?
The area of the inscribed circle is always less than the polygon's area. The ratio of these areas approaches 1 as the number of sides increases, providing another way to understand the limit relationship between polygons and circles.
40. What role does the concept of regular polygons play in the historical development of calculus?
Regular polygons were crucial in early attempts to calculate the area of a circle. Mathematicians like Archimedes used polygons with increasing numbers of sides to approximate circular areas, laying groundwork for the development of limits and integral calculus.
41. How can the area formula for regular polygons be used to derive the formula for the area of a circle?
By taking the limit of the regular polygon area formula as the number of sides approaches infinity, we can derive the formula for the area of a circle. This process demonstrates the powerful connection between discrete and continuous mathematics.
42. Why is it that doubling the number of sides of a regular polygon doesn't double its area?
Doubling the number of sides makes the polygon more circular but doesn't proportionally increase its area. The relationship is non-linear because the new polygon fills in only the small gaps between the original polygon and its circumscribed circle.
43. How does the concept of regular polygons connect to the study of trigonometric functions?
Regular polygons are intimately connected to trigonometric functions. The area formula involves the tangent function, and studying regular polygons with increasing numbers of sides helps visualize the behavior of trig functions for small angles.
44. How does the study of regular polygon areas relate to the concept of optimization in calculus?
Optimization problems often involve finding the maximum area for a given perimeter or minimum perimeter for a given area. Regular polygons play a key role in these problems, leading to important principles like the isoperimetric inequality.
45. Why is the area of a regular polygon always less than the square of its side length multiplied by the number of sides?
This inequality holds because the area formula accounts for the gaps between the polygon and its circumscribed square. It highlights how the actual area is always less than what a simple multiplication of side length and number of sides would suggest.
46. What's the connection between the area of a regular polygon and the concept of solid angles in 3D geometry?
Regular polygons in 3D space can be used to understand solid angles, which are the 3D analogue of planar angles. The area of a regular polygon on a unit sphere is directly related to the solid angle it subtends at the center, connecting 2D and 3D concepts.
47. How does the area of a regular polygon relate to its moment of inertia?
The moment of inertia of a regular polygon about its center is related to its area and the distribution of that area. Understanding the area formula is crucial for calculating moments of inertia, which are important in physics and engineering applications.
48. Why is the study of regular polygon areas important in computer graphics and digital image processing?
In computer graphics, regular polygons are often used to approximate curved shapes. Understanding their areas is crucial for accurate rendering and for algorithms that calculate properties of digital images, such as in image segmentation or feature detection.
49. How does the concept of duality in geometry relate to the areas of regular polygons?
Geometric duality, where points become lines and vice versa, has interesting implications for regular polygons. The dual of a regular polygon is another regular polygon, and understanding this relationship can provide insights into area calculations and geometric properties.
50. What role do regular polygons and their areas play in the study of symmetry groups?
Regular polygons are fundamental in the study of symmetry groups in mathematics. Their rotational and reflectional symmetries form the basis of many symmetry groups, and understanding their areas is crucial in applications of group theory to geometry.
51. How does the study of regular polygon areas contribute to our understanding of packing problems?
Packing problems, which involve fitting shapes efficiently into a space, often use regular polygons. Understanding their areas is crucial for calculating packing densities and efficiencies, with applications ranging from crystallography to efficient data storage.
52. What insights does the area formula for regular polygons provide about the nature of transcendental numbers?
The area formula involves both algebraic operations and the transcendental function tangent. This interplay provides a concrete geometric context for understanding transcendental numbers and their role in seemingly simple geometric shapes.
53. How does the concept of regular polygons and their areas extend to higher dimensional mathematics?
In higher dimensions, regular polygons generalize to regular polytopes. While visualization becomes challenging, the principles of symmetry and regularity used in polygon area calculations extend to volume and hypervolume calculations in these higher-dimensional analogues.
54. What role do regular polygons and their area calculations play in the field of computational geometry?
Regular polygons are fundamental shapes in computational geometry. Efficient algorithms for calculating their areas and properties are essential for applications in computer-aided design, geographic information systems, and computational physics simulations.
55. How does the study of regular polygon areas contribute to our understanding of the relationship between local and global properties in geometry?
Regular polygons demonstrate how local properties (side length, interior angles) determine global properties (total area, shape). This relationship is a microcosm of broader principles in differential geometry, where local curvature determines global shape, highlighting the deep connections between different scales of geometric analysis.

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