count the triangles in the image

Geometry Level 2

how many triangles are there ?


The answer is 27.

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1 solution

Saya Suka
Dec 12, 2020

Quantity of upright triangles.
= 10+6+3+1.
= 20.
Quantity of inverted triangles.
= 6+1.
= 7.
Total number of triangles.
= 20+7.
= 27


What is the general formula for a triangle with n upright triangles on one side?

Vijay Simha - 6 months ago

The sequence is in OEIS here , which links to this interesting survey of results and approaches to this problem.

Chris Lewis - 5 months, 4 weeks ago

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