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Two triangles - solution

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One segment is of length A and lays on the line La which is

y = kax + ca

The other segment is of length B and lays on the line Lb which is

y = kbx + cb

The red lines are parallel to La and Lb respectively, with the distances Da and Db.

One point where two red lines intersect is p and it defines two triangles. The area of the triangles are Da × A/2 and Db × B/2.

These areas should be the same, so:

Da × A/2 = Db × B/2
Da × A = Db × B
Db = A/B × Da

So Db is proportionate to Da and thus all p will be located on the two green "solution" lines, S1 and S2.

Note that it is irrelevant where on La and Lb the segments A and B are located. The areas of the triangles will be the same.

I have not made the equations for S1 and S2 yet, will do that later.


A way to formulate the solution would be like this:

Call the first segment A and the other segment B. See them as vectors, Va and Vb. Take the intersection between the lines going through A and B and call that point s.

The solution is then the points which lay on the two lines going through s and of which one has the same slope as Va + Vb and the other as Va - Vb.