Other Polygons

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Polygon any plane figure enclosed by straight lines. We see many types of polygons in nature and in life around us. Except for triangles &amp; quadrilaterals, polygons are named after the number of sides that they have. The word&rdquo; gon&rdquo; stands for side.

In geometry we study only convex polygons where every interior angle is less than 180 degrees. In concave polygons, some of the interior angles can be reflex angles.

Polygon – Many sided &ldquo;gon&rdquo;, Pentagon – 5 sides, Hexagon – 6, Heptagon – 7, Octagon – 8 sides, Nonagon – 9, Decagon- 10, Dodecagon – 12 etc.

If all the sides of a polygon &amp; all the interior angles are equal, then it is known as a &ldquo;regular&rdquo; polygon.

Hence in triangles the &ldquo;regular&rdquo; triangle in the Equilateral triangles. In quadrilaterals the &ldquo;regular&rdquo; quadrilateral is the Square. Regular polygons are also convex polygons where each interior angle is less than 180 degrees.

In all polygons, except the quadrilateral, equal sides automatically ensures equal interior angles. In quadrilaterals both square and rhombus have equal sides. Hence the additional criterion of equal angles has to be introduced to ensure that there is only one type of &ldquo;regular&rdquo; quadrilateral.

A polygon can be divided into a certain number of triangles by joining the vertices. There is a simple relation between the sides of the quadrilateral and the minimum number of triangles it can be divided into.

Hence the total of the internal angles of a polygon can be easily worked out. This also leads to a way of calculating the area of the polygon.

Many structures and shapes in nature are in the form of polygons.

Many flowers and creatures in the sea are similar to pentagons. The hexagonal shape of the cells of a beehive are well known. When several air bubbles join together, they form hexagons. Many chemical molecules are found to form shapes of different polygons.

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