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Rolling circle construction
Rolling_Circle_show_all shows a screen shot of all the components during construction.
In the final version the slider is kept out of view. (Be careful not to Hide it as this will reset its limits to GeoGebra default values.)
Point A is free on the y-axis and F is the midpoint of OA. The timer value t increases steadily from 0 to 3.5 then repeats.
Nested Ifs are used to set the value of k for the sub-ranges of t within the four phases: unwinding, delaying, re-winding, delaying.
The horizontal position of Point B is set by the value of k.
The circumference is calculated by multiplying the diameter OA by pi (3.14159...).
The Point E is such that the length of the anti-clockwise arc CE is the same length as the circumference less the length of the segment OC.
The Construction Protocol gives the construction steps in more detail (and includes comments - TODO).
The Animator class requires that the slider is named "t" and the controlled GeoGebra applet is name "Animated".
Links
Rolling_Circle main page
