This tool checks to see whether two angles are vertical angles. If they are not congruent, the angles are colored red. If they are congruent, the angles are colored green. Input is six points, where the first three select the first angle and the last three select the the second angle. Follow the convention for measuring angles used in Geogebra, where the vertex is denoted by the second of the three points selected. So, if you want to compare whether angle ABC is vertical to angle XYZ, select the points A, B, C, X, Y, Z.
This is designed as a tool to teach beginner geometry students. This is the reason for using six point rather than five is simple- I want my students to be in the habit of naming angles properly. Eventually, I plan on making other tools for comparing different types of angles (alternate interior angles for example) and it is important that I remain consistent according to the conventions that I teach. So, if you want to use this tool to compare your own constructions, you must have two points occupying the same location, ie. the intersection of two lines (if they are in fact vertical). I usually use the polygon tool to make two separate triangles and then drag one vertex to be superimposed with a vertex in the other triangle. I am aware that most people do not make constructions this way, so feel free to modify if you prefer that a tool that uses the minimal five points for vertical angles.
