# Graphing a Set of Polygons

Is there a way to graph a set of polygons? I am trying to use aggregate to get a set of triangles.

The simplified version is if I have 6 lists for the x-coordinate and y-coordinate of the 3 vertices. How can I graph the entire set? The best I have been able to manage is see all of them using a slider where “n” indexes the list of triangles.

Example:Graphing Calculator

For that I personally would use:

``````A=(A_x,A_y)
B=(B_x,B_y)
C=(C_x,C_y)
polygon(A,B,C)
``````

When you use lists of equal length, it matches elements together so you don’t need [n].

That is what I am using, but it only graphs one polygon.

For my A_x, A_y etc. they are lists of numbers, so without the [n] it fails to graph as it interprets it as a list of lists.

Oh sorry, you can’t use lists within lists. So you’d need:

``````polygon(A,B,C)
polygon(A,B,C)
polygon(A,B,C)
``````

Or you could join your lists (A,B,C) into one list L

``````polygon(L[1,4...9])
polygon(L[2,5...9])
polygon(L[3,6...9])
``````

There is a hacky way to plot a set of polygons. The main idea is to merge everything into a single list, manually “close” each polygon by repeating the first point, and “restart” the polygon drawing by inserting an undefined value between each.

In your graph, I joined (A,B,C,(0/0,0/0)) and manually re-indexed so that it would connect [a1,b1,c1,undefined; a2,b2,c2,undefined; …]: desmos.com/calculator/s0feftgikl

Here’s the same idea, but with the potential for an arbitrary number of triangles: desmos.com/calculator/a6lsmnwit4.

The calculator still thinks you are trying to draw a single polygon, though, so the fills can sometimes intersect with one another and “undraw” portions. If you define your coordinates manually, you can choose a consistent orientation to connect the dots and should be able to avoid this.

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That’s sneaky. I like it.

Very cool. I had this without the brilliance to slip in an undefined to reset… so it was just one massive polygon.

I wound up doing a different workaround with the equations of the 3 lines that’d connect the points as inequalities.

…and after a days work. I got a functional start to an activity.

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