Study Notes
Polygons are 2-dimensional closed shapes made of straight lines. They can be regular, with all sides and angles equal, or irregular. The sum of interior angles of a polygon with n sides is calculated as 180° × (n – 2). The sum of exterior angles of any polygon is always 360°.
- Triangle — A polygon with three sides. Example: An equilateral triangle has three equal sides and angles.
- Quadrilateral — A polygon with four sides. Example: A square has four equal sides and four right angles.
- Regular Polygon — A polygon with all sides and angles equal. Example: A regular pentagon has five equal sides and angles.
Exam Tips
Key Definitions to Remember
- A triangle has a sum of interior angles equal to 180°.
- A quadrilateral has a sum of interior angles equal to 360°.
- A regular polygon has all sides and angles equal.
Common Confusions
- Confusing the sum of interior angles with the sum of exterior angles.
- Misidentifying regular and irregular polygons.
Typical Exam Questions
- What is the sum of the interior angles of a hexagon? Answer: 720°
- How do you find the exterior angle of a regular pentagon? Answer: 360° ÷ 5 = 72°
- Calculate the sum of the interior angles of a polygon with 8 sides. Answer: 1080°
What Examiners Usually Test
- Understanding of angle sums in polygons.
- Ability to calculate unknown angles using polygon properties.