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By: Siyavula

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# Recognising and describing angles

Module by: Siyavula Uploaders. E-mail the author

## Memorandum

Do you remember what the word parallel means? Write down the definition for it:

Invariable

1. A: Yes

B: Yes

2. C

1.

1.1 Obtuse

1.2 Right angle

1.3 Rotation

1.4 Acute

BRAIN-TEASER!

1. Acute

Obtuse

Straight

Right angle

2. Class discussion:

## Content

Do you remember what the word parallel means? Write down the definition for it:

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

Let's begin with some "puzzles"!

Look at the sketches below and answer the questions that follow:

1. Indicate whether EF and GH are parallel to one another in figure

A: __________________________________________________________________

B: __________________________________________________________________

2. Which is the extension of F: C or K?

Do you still remember?

 indicates a line: AB indicates a line segment: EF indicates a radius: CD

Two lines that intersect form an angle.

The point where the lines meet is called the vertex.

We write this as: ÐABC

• Did you know?

The unit that we use for measuring angles is a degree. We measure

the size of the angle in degrees. We write an angle of 60 degrees as 60°.

You have to learn the different types of angles:

 Types of angles 1. The size of a rotation or full turn is 360° 2. A straight angle is a half turn and it is 180°. 3. A right angle is a quarter turn and it is 90°. 4. An acute angle is larger that 0°, but smaller than 90°. 5. An obtuse angle is larger than 90°, but smaller than 180°.

## ACTIVITY: Recognising and describing angles [LO 4.11]

1. How well do you know angles?

Work with a partner to see if the two of you can tell what the following angles are:

 1.1 _________________________________ 1.2 _________________________________ 1.3 _________________________________ 1.4 _________________________________

### Assessment

Learning Outcome 4:The learner will be able to use appropriate measuring units, instruments and formulae in a variety of contexts.

Assessment Standard 4.11: We know this when the learner recognises and describes angles in two-dimensional shapes, three-dimensional objects and the environment.

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