Area Of A Polygon
Chapter Name : Mensuration |
Sub Topic Code : 104_08_11_04_01 |
Topic Name : Area Of A Polygon |
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Sub Topic Name : Area Of A Polygon |
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Introduction
Just the way a quadrilateral was split into two triangles & its area was derived, area of any polygon may be arrived at using the triangulation technique of dividing the plane figure into a number of triangles, trapeziums, squares etc.
Pre-Requisites:
Areas of triangles, triangulation, trapezium
Activity:
Mirrors are available in different shapes these days. Take a mirror that has many sides & try to calculate its area by dividing it into different polygons. Try to calculate the area by dividing it in many ways.
Real Life Question:
How can the area of ‘The Pentagon’ in USA be calculated?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Polygon | A closed plane figure bounded by three or more line segments |
| Triangulation | The technique of dividing a quadrilateral into two triangles |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Weights | Most of the weights are hexagonal. Take a scale & trace them on the paper. Try to calculate its area |
Real life uses :
Life is not simple enough that all of the polygons would be only triangles & quadrilaterals. Most of the times, while building something or making something, you need to use the available space properly, which is when different shaped polygons come into picture
Places to visit :
Mirror Maze (You get to see mirrors shaped in different polygons)
Practical examples around us
| Examples | Explainations |
|---|---|
| Administrative office of any college | Most of the admin offices are exotic. Check one of them out. You will see different types of polygons over there. |
What you learn in Theory:
In general, a polygon with any number of sides can be divided into sufficient number of basic polygons, such as triangles by drawing diagonal/s or joining the corners, depending on the convenience.
What you learn in Practice:
Polygons with many sides are often found in many common objects in & around us. Although direct formulas are not available for them, it is possible to calculate the areas by dividing them into polygons who have formulas for their areas; mostly triangles