NRICH: Up and Across

Experiment with the interactivity of “rolling” regular polygons, and explore how the different positions of the dot affects its vertical and horizontal movement at each stage.

Take a look at the interactivities below which show regular polygons “rolling” along the horizontal surface, leaving a trace of the path of the dot.

In the first interactivity, the graph records the horizontal distance travelled by the dot.

In the second interactivity, the graph records the height of the dot over time.

Experiment by positioning the dot at the centre of the polygons, at one of the vertices or at the centre of one of the sides of the polygons and explore how this affects the two graphs.

Challenge:

Can you now work out what produced the following two graphs?
Can you work out how many sides the polygon had and where the dot was placed?
Try to explain how you worked it out.

Two graphs

Age 11 to 14


Algebra & Pre-Algebra, Functions & Graphs
Middle School, High School, Educator

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NRICH (University of Cambridge)

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Online Interactive Activity

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