# Polygon

## An Approximation of pi by the Law of Cosines

The approximation of π is a popular pastime of students of mathematics and I have started with the familiar age-old way, of fitting a regular polygon tightly in a circle of radius r. The vertices of the n-sided polygon are joined to the centre of the circle so that the angle subtended at the centre by each segment is 360/n. If n is sufficiently large, the perimeter of the polygon approaches the circumference 2πr of the circle and this approximation improves as the number of segments increases.

## Matchstick model to find out why football has hexagons and polygons

You might have already seen Arvind Gupta explaining the basic shapes in mathematics (& simple organic molecules) by a matchstick model. They are easier to make and very important tools helping learners visually the structures spatially.

## Octagon in a Square

Here is an another solution to the problem posed in November 2015 issue of At Right Angles.

## How to Prove It

In a previous issue of AtRiA (as part of the “Low Floor High Ceiling” series), questions had been posed and studied about polyominoes. In this article, we consider and prove two specific results concerning these objects, and make a few remarks about an open problem.

## Can a Circle be a Polygon?

Can a Circle be a Polygon?

Explanation:

How many sides does a circle have?

A circle could have: 1 curved side! or infinite sides (each side being very small) or no sides.

## Angles of a Pentagon

Let your students arrive at the sum of a pentagon's internal angles themselves, by folding paper into a pentagon.

Watch this simple video to see how it's done.

Here are some related resources on Teachers of India:

## The Four-Gon Family Tree

Classification is traditionally defined as the precinct of biologists. But classification has great pedagogical implications — based as it is on the properties of the objects being classified. A Ramachandran gives us a look at a familiar class of polygons — the quadrilaterals — and how they can be reorganized in a different way.

## Flatland ~ Edwin Abbott

This 1884 classic introduces the concept of 3 dimensions in a funny way. Made into an animation movie in 2007 by the same name, this book is presently made available under Project Gutenberg.

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