Do Now
List the first 10 multiples of:
| Find 10% of £230 Find 50% of £230 |
| Find the missing angles: a) b) (Hint: Angles on a straight line sum to…) |
100% | 230 |
10% | |
100% | 230 |
50% | |
÷ __
÷ __
Describe
Title: Interior Angles in Polygons
Objective:
To be able to calculate and use the sum of interior angles of polygons.
Key Words and Diagrams:
Interior
Sum
Angle
Polygon
Describe
Definition: Characteristics:
Examples: Non-Examples:
Angle
The amount of turn between one straight line and another.
Describe
What Angle Facts do you know?
Describe
What is a Polygon?
Describe
What is a Polygon?
Describe
Definition: Characteristics:
Examples: Non-Examples:
Polygon
Greek for “many angles”
A 2-Dimensional shape �made of 3 or more connected straight lines.
Whiteboards
Find the missing angle:
Why did you do these calculations?
40°
60°
Whiteboards
Find the missing angle:
Why did you do these calculations?
80°
60°
Whiteboards
Find the missing angle:
Why did you do this calculation?
30°
Whiteboards
Find the missing angle:
Why did you do this calculation?
60°
45°
I Do
Pick one vertex and connect it to all the others in the polygon.
How many interior triangles are there?
You Do
Pick one vertex and connect it to all the others in the polygon.
How many interior triangles are there?
Explore
Pick one vertex and connect it to all the others in the polygon.
How many interior triangles are there?
What is the same? What is different?
I Do
Pick one vertex and connect it to all the others in the polygon.
How many interior triangles are there?
What does this tell us about the interior angles in a rectangle?
You Do
Pick one vertex and connect it to all the others in the polygon.
How many interior triangles are there?
What does this tell us about the interior angles in a parallelogram?
Explore
What can we say about the sum of interior angles in a quadrilateral?
I Do
Pick one vertex and connect it to all the others in the polygon.
How many triangles are inside it?
What does this tell us about the interior angles?
You Do
Pick one vertex and connect it to all the others in the polygon.
How many triangles are inside it?
What does this tell us about the interior angles?
Extend your thinking:
Use your table to find the missing angle in the polygons.
145°
100°
130°
120°
100°
150
150°
a)
b)
c)
Summarise
Your friend is off today and has missed the lesson.
Tomorrow, they will ask you:
“How do you find the sum of interior �angles in a polygon?”
What will you say?
I Do
Find the missing angle in the polygon.
You Do
Find the missing angle in the polygon.
85°
I Do
Find the missing angle in the polygon.
You Do
Find the missing angle in the polygon.
115°
270°
50°