Take a pair of scissors to it

Geometry Level 1

Impossible! Yes, it's possible!

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Zandra Vinegar by Zandra Vinegar

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6 solutions

Zandra Vinegar Staff
Sep 4, 2015

And it's impossible to do it in fewer than 7 pieces!

119 Helpful 13 Interesting 22 Brilliant 5 Confused

The enunciantion doesn't let clear to us that we can drawn straight lines which don't have to starts and ends necessarily about the sides of the triangle.

José Bezerra Carvalho Júnior - 5 years, 9 months ago

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Actually, the failed attempts shows that it is an option.

Zachery Fournier - 5 years, 4 months ago

Relevant .

Relevant 2 .

Pi Han Goh - 5 years, 9 months ago

Any other attempt ?

Hari Om Sharma - 5 years, 9 months ago

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I find some are right angled triangles

Fathima Khaja - 5 years, 7 months ago

so this is a trial and error problem? you haven't shown us HOW you arrived at the solution.

Shakir Ahmad - 3 years ago

Can we show it's impossible to do so in less than 7 moves?

Aatman Supkar - 2 years, 11 months ago

is there like a formula

A Former Brilliant Member - 1 year, 11 months ago

I saw that answer on Ted Ed.

Eurus Li - 6 months ago
Samyak Jain
Sep 7, 2015

It can be done by joing midpoints of every side and repeating with triangles being formed

5 Helpful 1 Interesting 0 Brilliant 1 Confused

Moderator note:

As pointed out by Ivan, this solution is incorrect.

All triangles formed are similar to the original triangle (which means they are still obtuse), so this attempt fails.

Ivan Koswara - 5 years, 9 months ago

This leads to an infinite series that fails no matter how far you look into it.

Stephen Garinger - 4 years, 2 months ago
Chester Williams
Jan 13, 2018

It seems all solutions lie with the absolute midpoint-center of the triangle, working backwards to identify angles which produce solutions where all three angles are < 90° (essentially, variants of equilateral triangles where some of the triangles share one of its vertices at the midpoint-center, as shown in Zandra's solution).

2 Helpful 1 Interesting 0 Brilliant 0 Confused
S Broekhuis
Feb 9, 2021

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Eda Yıldırım
Jan 29, 2021

I guess I saw this problem in a Ted-Ed riddle. Here is the link: https://www.youtube.com/watch?v=4peuImhJj44&lc=Ugz-Cgu99VvPnYQfgzt4AaABAg

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Vivek Bajod
Sep 18, 2018

1 Thing is quite clear that triangle is obtuse triangle so after cutting every angle will be less than 90 and we can make infinite triangle of it

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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