• angle as an amount of turning

• identifying angles in 2-D and 3-D objects

• identifying angles in 2-D figures

• identifying right angles, angles greater than/ smaller than a right angle.

What will we learn today?

Geometry Basic Angles

We are going to learn about angles today!

Angles

An angle measures the amount of turn

There are different names for different angles.

As the angle increases, the name changes.

Extra information

Type of Angle Description

Not required to memorize as they are not in the syllabus.

Acute Angle an angle that is less than 90°

Right Angle an angle that is 90° exactly

Obtuse Angle an angle that is greater than 90° but less than 180°

Straight Angle an angle that is 180° exactly

Reflex Angle an angle that is greater than 180°

Right Angle

Right Angle

This angle is greater than 90°.

Right Angle

This angle is greater than 90°. This angle is smaller than 90°.

Straight Angle

This angle is greater than 90°.

How many right angles can you see in the figure?

How many right angles can you see in the figure?

There are two right angles.

How many angles are greater than 90°?

How many angles are greater than 90°?

There are four angles which are greater than 90°.

How many angles are smaller than 90°?

How many angles are smaller than 90°?

There are five angles which are smaller than 90°.

Are you ready to try out the questions?

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