1. 60° 70° 80° 90° 100° 110° 120° Angles recap Here are some angles.
[GM1.1 Core Starter]
Here are some angles.
20° ° ° °
60° ° °
90° ° 110° 120°
Which of the angles could:
a) fit together to make a straight line?
b) be vertices of the same triangle?
c) fit together round a point?
Preamble
A straightforward investigation involving pupils, as individuals or in pairs, working systematically.
Possible content
Sum of angles in a triangle, straight line and round a point. Working systematically. Elements of non-calculator additions.
Resources
None.
Solution/Notes
a) (all in degrees) 20, 30, 40, , 30, 50, , 30, 60, 70
30, 40, 50, , 40, , 50, 100
40, 60, 80, 100, , 70
120, 60etc.
b) (all in degrees) 120, 40, , 20, , 30, 50
, 20, , 40, , 20, 70
90, 30, , 70, , 60, 40
70, 60, etc.
c) (all in degrees)
, 110, 100, , 40, 60, 110, 100, , 100, 50, 40, 20, 30
120, 90, 60, 50, 40, etc.
Original Material © Cambridge University Press 2010
Original Material © Cambridge University Press 2010