Regular Polygon in Maths – Definition, Area Formula, and Solved Examples

The concept of Regular Polygon plays a key role in mathematics and is widely applicable to both real-life situations and exam scenarios.

What Is a Regular Polygon?

A regular polygon is defined as a two-dimensional closed shape made up of straight lines, where all sides are equal in length and all interior angles are equal in measure. You’ll find this concept applied in geometry basics, symmetrical design, and real-life pattern recognition. Equilateral triangles and squares are the simplest examples of regular polygons.

Key Formula for Regular Polygon

Here’s the standard formula for the area of a regular polygon with n sides of length s:

Area = \(\dfrac{n \times s^2}{4 \times \tan\left(\dfrac{\pi}{n}\right)}\)

Perimeter = \(n \times s\)

Properties of Regular Polygons

• All sides are equal in length.
• All interior angles are equal in measure.
• The sum of all exterior angles is always 360°.
• Number of lines of symmetry = number of sides.
• Each interior angle = \(\dfrac{(n-2) \times 180^\circ}{n}\), where n = number of sides.
• Each exterior angle = \(\dfrac{360^\circ}{n}\).

Difference Between Regular and Irregular Polygons

Step-by-Step Illustration

1. Suppose you have a regular hexagon (6 sides) with each side = 4 cm.
   
   Area = \(\dfrac{6 \times 4^2}{4 \times \tan(\dfrac{\pi}{6})}\)
2. Solve numerator and denominator:
   
   \(6 \times 16 = 96\)
   \(4 \times \tan(30^\circ) \approx 4 \times 0.577 = 2.308\)
3. Calculate final area:
   
   \(96 \div 2.308 \approx 41.6\) cm²

Speed Trick or Vedic Shortcut

Here’s a quick shortcut: If you know the side length and the number of sides, you can instantly find the exterior angle using \( \frac{360^\circ}{n} \). For MCQs, just divide 360 by the number of sides of the regular polygon.

Example Trick: For a regular pentagon, \( \frac{360}{5} = 72^\circ \) (each exterior angle).

Tricks like these boost calculation speed—very handy in timed exams! Vedantu’s live Maths classes share more such geometric hacks.

Try These Yourself

• Name three regular polygons commonly found in daily life.
• Find the sum of the interior angles of a regular octagon.
• What is each interior angle of a regular dodecagon (12 sides)?
• If each side of a regular pentagon is 6 cm, what is its perimeter?

Frequent Errors and Misunderstandings

• Confusing rectangles and rhombuses with regular polygons.
• Forgetting to use radians or degrees correctly in area formulas.
• Mistaking irregular polygons for regular ones in diagrams.

Relation to Other Concepts

The idea of regular polygon connects closely with topics such as types of polygons and properties of polygons. Mastering this helps with recognizing geometric symmetry, solving for area and perimeter, and tackling advanced geometry problems.

Classroom Tip

A quick way to remember regular polygons: “Equal sides, equal angles—makes a perfect regular shape.” Try drawing polygons and checking their symmetry. Vedantu teachers use cut-outs and folding tricks to help see symmetry live in class.

Wrapping It All Up

We explored regular polygons—from definition and formulas to properties, examples, mistakes, and their link to other geometry topics. Continue practicing area and angle sums, and explore regular polygons in real-life designs. For more tricks and deeper explanations, keep learning on Vedantu!