Polygons
Chapter Name : Understanding Quadrilateral |
Sub Topic Code : 104_08_03_02_05 |
Topic Name : Polygons |
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Sub Topic Name : Angle Sum Property |
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Introduction
For any given polygon, the sum of all the angles of the included angle remains constant irrespective of the total number of sides. For a quadrilateral, the sum is equal to 360 deg.
Pre-Requisites:
Basic knowledge about polygons
Activity:
The interior unknown angle of a polygon can be measured by dividing it into basic polygons like triangles and using the angle sum property of the triangle.
Real Life Question:
When the corners of all the vertices of a quadrilateral paper pieces are joined together, they fit perfectly like the pieces of puzzle. Why does this happen with all quadrilaterals?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Total interior angle | Sum of all interior angles |
| Interior angle | Angle inside a polygon formed between two adjacent sides |
| Polygon | A simple closed curve classified according to number of sides and vertices |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Scissors, paper, sketches, ruler, protractor | Polygons are drawn on the paper as plane surfaces increasing one vertex and a side at a time. Different shapes are formed. Draw diagonals of the polygons using ruler. Find the angles using a protractor. |
Real life uses :
Computer screens, TV screens, black boards, construction sites, fields all have polygon surfaces
Practical examples around us
| Examples | Explainations |
|---|---|
| Black boards | They are convex polygons. They are equiangular and some might even be equilateral depending on shape |
| Computer monitors | The screen is a convex polygon. |
What you learn in Theory:
An Intro into interior angle and sum of interior angles of a polygon.
What you learn in Practice:
A polygon is defined by the number of its sides and vertices it has. The sum of all the interior angles of remains constant for given number of sides. These properties are very important when dealing with complex geometrical designs like air planes, aerofoils etc.