Lesson 28 Graph of the rotating arm

Lesson plan

Piagetian Level  
3 B
Mature
Formal






‘you are asking us to extend the idea of ‘sine’ outside the context of triangles, and into rotations in general’
‘between O°and 20° and 160°and 180° the graph becomes a straight line: as the arm approaches 90° it’s got no further to go’
3A
Early
Formal
‘angles that have sine = 0.7 are both 45° and 135° — then to get sine 1000° you have to imagine the curves repeating themselves fo the right’
‘sine of -10° is the same as sine 350°'
2B*
Concrete
Generalisation
‘the graph increases fastest to begin with and gets flatter and flatter towards 90°

Interpreting angle as a measure of turn in relation fo sine ratio
2B
Mature
concrete
Mid
concrete
Episode 1
Sine ratios in 1st two quadrants

Episode 2
Sines beyond 180°

License

Thinking Mathematics Lessons Copyright © by Michael Shayer and Mundher Adhami. All Rights Reserved.

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