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Lesson 1: Understand and use basic angle rules and notation
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1. 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...
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2. Extension Activity!
- *The sum of angles in a regular polygon*
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Lesson 1: Understand and use basic angle rules and notation
A Ahmed, Apr 13, 2021
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.
We will be moving the pink point to each of the crosses and note down any observations.
Questions
What do you notice about those two angles (α and β) on a straight line? What do they add up to?
Is there a difference between the different coloured crosses?
What angle symbol do we find when the pink dot is on the green diamond shapes? What does this symbol represent?
Does the length of the line affect the angle?
*Quickfire Challenge!*
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.
Questions
What is a polygon?
What do we mean by regular?
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?
Can you work out the size of each interior angle of a regular polygon?
What is the exterior angle of each regular polygon?
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