Different kinds of angles, naming an angle and angles pairs for grade 7 third quarter

2. • The space between two
intersecting straight lines, at the
point in which they meet.
• The point where they meet is
called the vertex.
• Angles are measured in degrees.

4. Acute (>0, <90 degrees)
Right (90 degrees)
Obtuse (>90, <180 degrees)
Straight (180 degrees)
Reflex (>180, <360 degrees)
Revolution (360 degrees)

5. The internal measurement of two straight lines, where the
angle measures more than 0 but less than 90.

6. A right angle is equal to 90

7. The internal measurement of two straight lines, where the
angle measures more than 90 but less than 180.

8. A straight angle is equal to 180

9. The external measurement of two straight lines, where the
angle measures more than 180 but less than 360.

10. A full rotation of 360

11. A right angle
A
An acute angle
B
An obtuse angle
C

12. An acute angle
B

13. An acute angle
A
A reflex angle
B
A right angle
C

14. A right angle
C

15. An acute angle
A
An obtuse angle
B
A right angle
C

16. An acute angle
A

17. A straight angle
A
A reflex angle
B
A right angle
C

18. A straight angle
A

31. Examples
a)
Find the missing angles, diagrams are not drawn accurately:
124˚
180 - 124 = 56˚
x
˚
Adjacent angles on a
straight line sum to 180˚
b)
101˚
101 + 112 + 52 = 265˚
x
˚
Angles at a point sum to 360˚
112˚
52˚
360 - 265 = 95˚

32. 1. 2.
3. 4.
131˚
Practice questions
Find the missing angles, diagrams are not drawn accurately:
117˚
x˚
x
˚
109˚ 27˚
46˚
x
˚
116˚
x˚