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Australia
Year 4

9.05 Name and classify angles

Lesson

Are you ready?

Being able to  compare angles  can help us in this lesson. Let's try this problem to review.

Examples

Example 1

Which of these angles is larger?

A
Image of a right angle.
B
Image of an obtuse angle
Worked Solution
Create a strategy

Choose the option with a larger turn between the lines.

Apply the idea

The answer is option B.

Idea summary

Angles can be compared by how large the turn is between the lines.

Right angles

This video looks at right angles as quarter turns measuring 90\degree. We also look at angles that are bigger or smaller than 90\degree.

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Examples

Example 2

Which of the following is a right angle?

A
A right angle
B
An acute angle.
Worked Solution
Create a strategy

Look for the angle with a small square in the corner.

Apply the idea

Option A has a small square at the corner, so the answer is option A.

Idea summary

A quarter turn is called a right angle.

Outcomes

ACMMG089

Compare angles and classify them as equal to, greater than, or less than, a right angle

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