# 9Y/T Band: Unit: Angles in polygons

## 1. Interior angles in a triangle

In this lesson, you will learn about the interior angles in a triangle, and how to find unknown angles in various types of triangles.

## 2. Categorising and defining polygons

In this lesson, you will learn about the key terminology involved in describing polygons, and begin to categorise polygons, based on certain properties.

## 3. Building shapes from triangles (Part 1)

In this lesson, you will learn how to arrange triangles to form polygons (part I).

## 4. Building shapes from triangles (Part 2)

In this lesson, you will learn how to arrange triangles to form polygons (part II).

## 5. Polygons and triangles

In this lesson, you will learn that the sum of the interior angles of a polygon can be found using triangles.

## 6. Generalising angles in polygons (Part 1)

In this lesson, you will learn how to generalise the sum of the interior angles in an n-sided polygon.

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