1. Angles and Properties

2. Definition
An Angle: – Is made when two lines meet at a common end point.
The amount of turning needed to make an Angle is given in Degree’s
Angle is 35o

3. Angle Types Acute Angles are between 0o to 90o
Obtuse Angles are between 90o to180o
Reflex Angles are over 180o
A Right Angle equals 90o

4. Angle Names The angle shown is called eitherP Q R
The angle shown is called either
1) Angle OR
2) Angle OR
3) Angle
Note: The middle letter is at the corner or Vertex of the angle.

5. Look at each of these angles.
Practice
Look at each of these angles.
Decide if each is A acute, O obtuse or R right-angled. 1 2 A O 3 5 4 A R R 6 7 A A O 8

6. Use the letters to name these angles
Practice
Use the letters to name these angles 1 P T C 2 D R B

7. 1 2 3 4 5 6 7 8 9 Acute Acute Obtuse Right Obtuse Reflex Obtuse Acute

8. Measuring Angles

9. What do we use to help us? A protractor
Here is a standard protractor like you use in the classroom.

10. When we use a protractor, we need to line it up correctly.
You need to make sure the protractor is lined up correctly.
Is this ready to measure the angle?

11. Look for the upside down ‘T’ in the middle of the straight line on your protractor.
This needs to be exactly on the corner or vertex of your angle.

12. We need to remember..... It doesn’t matter which way round the
angle is, you
ALWAYS need
to line the upside
down ‘T’ to the vertex
of the angle.

13. Read from the 0°, and follow the inner set of numbers.

14. Once you reach 30° you need to be careful!!!
You then need to look at the 1° markings on the outer set of numbers.

15. What does it measure?
This angle measures 35°.

16. Using a Protractor 1 50o 2 67o 0 on the inside so use inside scale
0 on the outside so use outside scale

17. Drawing Angles

18. Step One
Get a protractor

19. Step Two
Put 3 dots

20. Step Three
Move the Protractor

21. Step Four
Get a ruler

22. Step Five
Draw a line along the bottom

23. Step Six
Draw a line along the side

24. Step Seven
Draw a curved arc between the lines

25. Angles Properties Some angles can be worked out without measuring 1)
Angles on a straight line add up to 180o
a + b = 180o a b
E.G
a + 50o = 180o
a = 130o a
50o

26. Angles around a point add up to 360o2)
Angles around a point add up to 360o
E.G a a
a o = 360o
a = 150o b 90 c
120
a + b + c = 360o 3)
Vertically opposite Angles are equal
E.G a b a
80o
a = 80o
ao = bo