Free string

Topic:Algebra, Congruence, Constructions, Geometry, Quadratic Equations, Geometric Transformations

This activity belongs to the GeoGebra book Linkages. GeoGebra allows two types of scripts:

Those specific to this Dynamic Geometry program, made up of successive commands lines. They are the ones we have used so far, simple and without the need to know programming.
Those typical of programming in Javascript.

As a sample of the use of the latter, we extend the open chain of the previous construction from 4 points to 40 points (A1, ..., A40, all free). By hiding the intermediate points (A2, ..., A39), which are now left without a script, we get the result to simulate a string. As A1 moves, the wave of its movement is transmitted through all intermediate points up to A40, and vice versa.

The Javascript code used is detailed below. When moving A1: var j = 2; while (j <= 40) { ggbApplet.evalCommand("SetValue(A" + j + ", Intersect(Ray(A" + (j-1) + ", A" + j + "), Circle(A" + (j-1) + " ,1)))"); j++; } When moving A40: var j = 39; while (j > 0) { ggbApplet.evalCommand("SetValue(A" + j + ", Intersect(Ray(A" + (j+1) + ", A" + j + "), Circle(A" + (j+1) + " ,1)))"); j--; }

Author of the construction of GeoGebra: Rafael Losada

Free string

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