Interior angles of polygons

Key notes:

Interior Angles of Polygons

  1. Definition of Polygons:
    • A polygon is a closed figure formed by three or more straight line segments (sides) that do not cross each other.
  2. Types of Polygons:
    • Regular Polygons: All sides and angles are equal (e.g., equilateral triangle, square).
    • Irregular Polygons: Sides and angles are not all equal (e.g., trapezoid, rectangle).
  3. Interior Angles:
    • The interior angles are the angles formed inside a polygon at each vertex where two sides meet.
  4. Sum of Interior Angles:
    • The sum of the interior angles of a polygon can be calculated using the formula: Sum of interior angles=(n−2)×180° where n is the number of sides in the polygon.

Learn with an example

📢 What is the sum of the angle measures in this shape?

____°

Find out how many triangles make up a pentagon.

A pentagon is made up of 3 triangles, which each have 180°. Multiply.

3 × 180° = 540°

The angle measures of a pentagon add up to 540°.

📢 What is the sum of the angle measures in this shape?

_____°

Find out how many triangles make up a hexagon.

A hexagon is made up of 4 triangles, which each have 180°. Multiply.

4 × 180° = 720°

The angle measures of a hexagon add up to 720°.

📢 What is the sum of the angle measures in this shape?

______°

Find out how many triangles make up a quadrilateral.

A quadrilateral is made up of 2 triangles, which each have 180°. Multiply.

2 × 180° = 360°

The angle measures of a quadrilateral add up to 360°.

Let’s practice!🖊️