Angles

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 2

Good morning!

Planning: 

• Learning goals 
• Worksheet/Homework check
• Angles
• Angle notation
• Measuring angles

Learning goals 

At the end of this lessons I can:

• Identify different kinds of angles
• Use the correct notation when working with angles
• Measure angles with my protractor/geotriangle 

What different kinds of angles are there?

Angles

Examples in real life context

Acute angle

Right angle

Obtuse angle

Revolution

Reflex angle

Straight angle

90°

Between 0° and 90°

Between 90° and 180°

180°

Between 180 and 360°

360°

Angle notation

Three point notation: You refer to angles using a point on each arm and the vertex between them

Angle notation

Three point notation: You refer to angles using a point on each arm and the vertex between them

Arms

Angle notation

Three point notation: You refer to angles using a point on each arm and the vertex between them

Green angle notation : 

Blue angle notation : 

Red angle notation : 

Angle notation

Three point notation: You refer to angles using a point on each arm and the vertex between them

Green angle notation: 

∠ADB           ∠BDA

Blue angle notation: 

∠BDC          ∠CDB

Red angle notation:

Reflex  of ∠ADC           reflex of ∠CDA

Angles and degrees

Right angle

Straight angle

Acute angle

Obtuse angle

∠A=90°

∠B=180°

∠C<90°

90°<∠D<180°

What angle do you see?

Measuring angles

1. What kind of angle is it? What amount of degrees could it be? 

(Ex. An acute angle MUST be between 0° and 90°)

2. Measure with your protractor or geotriangle

3. Check: does my measurement make sense with step 1? 

Worktime

You work neatly by…

1. … reading the theory (again) before asking a question to your classmate.
2. … raising a hand before asking a question to the teacher.
3. … if the teacher is busy, remember your question and move on.
   

Assignments:

Textbook 

Page 111 Activity

Worksheet 

page 115 # 4-7

Extra:

Exercises worksheet 2

Now I can…

1. … recognize right, acute, obtuse and straight angles.
   
2. … indicate angles in degrees.
3.  ...Use the correct notation when working with angles.
4. ....

Reflection