The pattern of possible numbers of non-congruent triangles for different size dot grids.

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If I have four dots, arranged in two rows of two to make a square, and I draw a triangle by joining three of the dots, there are four triangles I can draw, but they are all the same shape (they are congruent).
If I start with nine dots, arranged in three rows of three to make a square, how many different (non-congruent) triangles is it possible to draw?
What if I start with a square formed of sixteen dots?
Can you generalise for n2 dots?







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  • Do the triangles have to be made of as many dots as n+1
    – Pi_die_die
    Jul 21 at 10:45










  • Start with a simpler problem that you cannot yet solve: How many nondegenerate triangles are there in a grid of $n^2$ points?
    – Christian Blatter
    Jul 21 at 13:55










  • Can the triangles be turned in space? Or only in the plane? I.e., do you distinguish them according to chirality?
    – joriki
    Jul 21 at 14:38










  • The triangles you count for each number of dots can not be rotations of reflection of each other.
    – PERCIVAL
    Jul 22 at 13:28














up vote
0
down vote

favorite
1












If I have four dots, arranged in two rows of two to make a square, and I draw a triangle by joining three of the dots, there are four triangles I can draw, but they are all the same shape (they are congruent).
If I start with nine dots, arranged in three rows of three to make a square, how many different (non-congruent) triangles is it possible to draw?
What if I start with a square formed of sixteen dots?
Can you generalise for n2 dots?







share|cite|improve this question





















  • Do the triangles have to be made of as many dots as n+1
    – Pi_die_die
    Jul 21 at 10:45










  • Start with a simpler problem that you cannot yet solve: How many nondegenerate triangles are there in a grid of $n^2$ points?
    – Christian Blatter
    Jul 21 at 13:55










  • Can the triangles be turned in space? Or only in the plane? I.e., do you distinguish them according to chirality?
    – joriki
    Jul 21 at 14:38










  • The triangles you count for each number of dots can not be rotations of reflection of each other.
    – PERCIVAL
    Jul 22 at 13:28












up vote
0
down vote

favorite
1









up vote
0
down vote

favorite
1






1





If I have four dots, arranged in two rows of two to make a square, and I draw a triangle by joining three of the dots, there are four triangles I can draw, but they are all the same shape (they are congruent).
If I start with nine dots, arranged in three rows of three to make a square, how many different (non-congruent) triangles is it possible to draw?
What if I start with a square formed of sixteen dots?
Can you generalise for n2 dots?







share|cite|improve this question













If I have four dots, arranged in two rows of two to make a square, and I draw a triangle by joining three of the dots, there are four triangles I can draw, but they are all the same shape (they are congruent).
If I start with nine dots, arranged in three rows of three to make a square, how many different (non-congruent) triangles is it possible to draw?
What if I start with a square formed of sixteen dots?
Can you generalise for n2 dots?









share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Jul 21 at 10:18
























asked Jul 21 at 8:28









PERCIVAL

94




94











  • Do the triangles have to be made of as many dots as n+1
    – Pi_die_die
    Jul 21 at 10:45










  • Start with a simpler problem that you cannot yet solve: How many nondegenerate triangles are there in a grid of $n^2$ points?
    – Christian Blatter
    Jul 21 at 13:55










  • Can the triangles be turned in space? Or only in the plane? I.e., do you distinguish them according to chirality?
    – joriki
    Jul 21 at 14:38










  • The triangles you count for each number of dots can not be rotations of reflection of each other.
    – PERCIVAL
    Jul 22 at 13:28
















  • Do the triangles have to be made of as many dots as n+1
    – Pi_die_die
    Jul 21 at 10:45










  • Start with a simpler problem that you cannot yet solve: How many nondegenerate triangles are there in a grid of $n^2$ points?
    – Christian Blatter
    Jul 21 at 13:55










  • Can the triangles be turned in space? Or only in the plane? I.e., do you distinguish them according to chirality?
    – joriki
    Jul 21 at 14:38










  • The triangles you count for each number of dots can not be rotations of reflection of each other.
    – PERCIVAL
    Jul 22 at 13:28















Do the triangles have to be made of as many dots as n+1
– Pi_die_die
Jul 21 at 10:45




Do the triangles have to be made of as many dots as n+1
– Pi_die_die
Jul 21 at 10:45












Start with a simpler problem that you cannot yet solve: How many nondegenerate triangles are there in a grid of $n^2$ points?
– Christian Blatter
Jul 21 at 13:55




Start with a simpler problem that you cannot yet solve: How many nondegenerate triangles are there in a grid of $n^2$ points?
– Christian Blatter
Jul 21 at 13:55












Can the triangles be turned in space? Or only in the plane? I.e., do you distinguish them according to chirality?
– joriki
Jul 21 at 14:38




Can the triangles be turned in space? Or only in the plane? I.e., do you distinguish them according to chirality?
– joriki
Jul 21 at 14:38












The triangles you count for each number of dots can not be rotations of reflection of each other.
– PERCIVAL
Jul 22 at 13:28




The triangles you count for each number of dots can not be rotations of reflection of each other.
– PERCIVAL
Jul 22 at 13:28















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