Close to triangular

Drawing a triangle is not always as easy as you might think!
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Problem



Here are the coordinates of nine points. It is possible to draw a triangle so that the shortest distance from each point to the triangle is at most one unit.

$(0, 0)$

$(8, 2)$

$(7, 8)$

$(170, 180)$

$(340, 360)$

$(2001, 1000)$

$(1500, 750)$

$(3000, 2000)$

$(4002, 2000)$

Can you find a suitable triangle? Is there more than one possibility?

Given three points, it is always possible to draw different triangles with edges passing through those three points - here are some examples of triangles going through the same three points:

Image
Close to triangular
Can you convince yourself that there are always infinitely many such triangles?

Here are some examples of different triangles going through the same set of four points:

Image
Close to triangular


Is it always possible to draw triangles through a set of four points, whatever their position?

Investigate some examples and explain your findings.

What happens when we try to draw triangles through five points?