Is it possible to divide an equilateral triangle into 5 equal (i.e., obtainable
from each other by a rigid motion) parts?
Splitting an Equilateral Triangle into 5 Equal Parts
dissectiongeometry
Related Solutions
Why $17$ equal part? In (i) you divide triangle into $4=5-1$ parts. Do the same with $16=17-1$ parts (it's easy - divide each side into $4$ parts).
Recently Pavel Guzenko found a way to divide an equilateral triangle into 15 congruent parts (and also into 30 congruent parts).
Best Answer
The answer is "yes", it is possible to divide equilateral triangle into $5$ equal parts, see the picture below which comes from here: https://ru-math.livejournal.com/831851.html