Arcs

The use of this tool is exemplified in Euclidean Geometry and in Families of Graphs.

The configuration panel of ARCS may have as many lines as desired. Each line defines an arc and looks like this:

[u,v]R[a0,a]'S':colour=red

The configuration of an arc consists of expressions, separated from each other by : , that define different aspects of the arc.

The configuration line of an arc starts with the coordinates (in square brakets) of the center of the arc, then the radius of the arc and finally the initial angle and the total degrees spanned by the arc. These two angles are surrounded by square brackets. For example: [0,0]R[10,30] represents the arc centered at the origin, with radius R, that starts at 10 degrees and ends at 10+30=40 degrees. The coordinates of the center, the radius and the angles may be expressions in terms of the parameters and variables. After that, a chain of strings, flanked by single quotes ' , and numbers or numerical expressions separated from each other by a + sign may come (see the documentation of TEXTS for a detailed description of this feature). The strings and numbers will appear starting at the center of the arc. Then an expression colour=red may come, defining the colour of the segment (red in this case).

The following example shows an arc A with center at the point [u,v], of radius R, starting at a degrees and spanning a total of b degrees. The arc changes it's radius and it's angles when the user changes the values of the parameters u, v, R, a and b. The number in red is the length of the arc.

There is an alternate way to define an arc. It starts also with the center and the radius, but instead of the angles, two more points are given from which the initial and final angles are determined. For example: [0,0]R[3,1][-2,2] defines an arc with center at the origin and radius R, that goes from the segment [0,0][3,1] to the segment [0,0][-2,2]. The following example illustrates the use of this way of configurating an arc.

In this type of configuration the arcs span at the most 180 degrees.

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	Ministerio de Educación, Cultura y Deporte. Año 2000