Lesson 1: Understand and use basic angle rules and notation
This book will explore 5 angle rules: 1. Angles on a straight line 2. Angles around a point 3. Vertically opposite angles 4. Angles in a triangle 5. Angles in a quadrilateral
Table of Contents
- Angle(s) Rules!
- 1(a) Angles on a straight line add up to...
- 1(b) Angles on a straight line add up to...
- 2. Angles around a point add up to...
- 3. Vertically opposite angles are...
- 4. Angles in a triangle add up to...
- 5. Angles in a quadrilateral add up to...
- Extension Activity!
- *The sum of angles in a regular polygon*
1(a) Angles on a straight line add up to...
For this activity, we will be dragging the pink point around to see what happens to the angles α and β as well as what we can observe.[br][br]We will be moving the pink point to each of the crosses and note down any observations. [br][br][u]Questions[/u][br][br]What do you notice about those two angles (α and β) on a straight line? What do they add up to?[br]Is there a difference between the different coloured crosses? [br]What angle symbol do we find when the pink dot is on the green diamond shapes? What does this symbol represent? [br]Does the length of the line affect the angle?[br][br][u]*Quickfire Challenge!*[/u] [br][br]Let us hide one of the angles (α or β) and see if you can work out the missing angle!
How do you know?
*The sum of angles in a regular polygon*
What is the sum of angles in a regular polygon?
Have a play with the slider which corresponds to the number of vertices (corners) on a polygon.[br][br][u]Questions[/u][br][br]What is a polygon?[br]What do we mean by regular?[br]What is the sum of angles for regular polygons? Are they the same or different when n (number of vertices) is changed? Can you explain why?[br]Can you work out the size of each interior angle of a regular polygon?[br]What is the exterior angle of each regular polygon?[br][br]