# Unit: Angles in polygons

## Lessons:

12 lessons

### 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.

### 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.

### Building shapes from triangles (Part 1)

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

### Building shapes from triangles (Part 2)

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

### Polygons and triangles

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

### 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.

### Generalising angles in polygons (Part 2)

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

### Finding missing angles in polygons

In this lesson, you will learn how to find an unknown angle in a polygon.

### Exterior angles

In this lesson, you will learn about exterior angles, and how they sum to 360 degrees.

### Regular interior and exterior angles (and mean of irregular)

In this lesson, you will learn how to calculate the mean interior and exterior angles of n-sided polygons, and solve problems based on these formulae.

### Generalising and comparing generalisations

In this lesson, you will combine everything learnt so far about angles in polygons to compare how specific examples relate to generalised cases.

### Angle notation and problem solving

In this lesson, you will learn about how to problem solve with angles in polygons, along with learning notations for referring to angles.