STORY OF THE POLYGON CLASS 8 NCERT QUADRILATERALS
📚 "The Tale of Polygons – Straight Lines, Sharp Minds!"
👋 Hello, I am Polygon – The Many-Sided Wonder!
Greetings, little mathematicians! I am Polygon, a closed figure made only with straight lines. You won’t find any curves or bends in me – I’m all sharp and precise.
My name comes from Greek: “poly” means many, and “gon” means angles. So yes – I’m the shape with many angles and sides!
🧾 My Definition: What Makes Me a Polygon?
To be part of my family, a shape must have:
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Only straight sides (called line segments or edges)
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A closed figure – no open ends
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Each side connects to exactly two other sides at endpoints (called vertices)
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No crossing or overlapping sides (for simple polygons)
🧩 How Many Types Am I?
Based on My Sides and Angles, I Come in Two Flavors:
1. Regular Polygon:
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All sides are equal
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All interior angles are equal
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I’m the neatest one in the family!
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Example: Equilateral triangle, square, regular hexagon
2. Irregular Polygon:
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Sides and angles are not all equal
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I love variety!
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Example: Scalene triangle, trapezium
🔢 My Many Forms – I Grow With Every Side!
Number of Sides (n) | Name | Interior Angle Sum | Each Angle (if Regular) |
---|---|---|---|
3 | Triangle | (3−2) × 180 = 180° | 60° |
4 | Quadrilateral | (4−2) × 180 = 360° | 90° |
5 | Pentagon | (5−2) × 180 = 540° | 108° |
6 | Hexagon | (6−2) × 180 = 720° | 120° |
7 | Heptagon | (7−2) × 180 = 900° | ~128.57° |
8 | Octagon | (8−2) × 180 = 1080° | 135° |
9 | Nonagon | (9−2) × 180 = 1260° | 140° |
10 | Decagon | (10−2) × 180 = 1440° | 144° |
📐 My Angle Secrets
🔸 Interior Angle Sum Formula:
Sum = (n – 2) × 180°
(Where n is the number of sides)
🔹 Each Interior Angle (if Regular):
Each angle = [(n – 2) × 180°] ÷ n
🔸 Exterior Angle Sum:
No matter how many sides I have, if you go around me and measure one exterior angle at each vertex, the total is always:
360°
🎭 Meet My Famous Members
🔺 I’m Triangle – the smallest polygon
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3 sides, 3 angles
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Total angle = 180°
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I can be equilateral, isosceles, or scalene
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I build strength into structures!
🔷 I’m Quadrilateral – four-sided, full of variety
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Total angle = 360°
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I include square, rectangle, rhombus, kite, and trapezium
🟠 I’m Pentagon – 5 sides
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Angle sum = 540°
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If regular, each angle is 108°
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You’ll find me in nature (like in starfish)!
🔵 I’m Hexagon – honeybee’s favorite
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6 sides, angle sum = 720°
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Each angle (if regular) = 120°
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Found in beehives and snowflakes!
🟣 I’m Octagon – stop right there!
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8 sides, angle sum = 1080°
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Found in traffic signs and designs
💡 Why I Matter
I’m not just a shape – I’m geometry's best friend. Architects, artists, engineers, and even nature uses me.
Whether in a tile floor, a soccer ball, a honeycomb, or a windowpane – I’m everywhere.
🌟 Polygon’s Final Words
"With every extra side, I grow stronger and more complex.
But I always follow the rule: be closed, be straight, and never bend.
I’m a polygon – proud, precise, and present in the world all around you!"
HAPPY LEARNING
INSTITUTE OF THE CREATIVE SCIENCES, 9818541252.
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