[Math] Corners are cut off from an equilateral triangle to produce a regular hexagon. Are the sides trisected

geometryproof-explanation

The corners are cut off from an equilateral triangle to produce a regular hexagon. Are the sides of the triangle trisected?

In the actual question, the first line was exactly the same. It was then asked to find the ratio of area of the resulting hexagon and the original triangle. In the several solutions of this problem which I found on the internet, they had started with taking the sides of triangle as trisected by this operation and hence the side length of the hexagon would also be equal to one-third of the side length of triangle.

I have seen some variations of this problem where they had explicitly mentioned that the side was trisected and then hexagon was formed.

On stackexchange, there are problems in which they started by trisecting the sides (they mentioned it in the title) and getting a regular polygon.

My question is, if we cut off corners from the equilateral triangle to form regular hexagon, is it going to trisect the sides of triangle or not?

Best Answer

Yes. If we cut off corners to create a regular hexagon, then each angle of the hexagon is $120^\circ$, meaning that each angle of each removed triangle is $60^\circ$, so these triangles are equilateral.

Now all sides of the hexagon are equal. Each triangle you removed shares a side with the hexagon, so all its sides are equal to the side length of the hexagon. Thus the three parts of each side of the original triangle are equal - two of them are sides of removed triangles and the third is a side of the hexagon.