The interior angles in a triangle always add up to 180º. An equilateral triangle has 3 sides of equal length. The dashes on the lines show they are equal in length. All of the angles are also equal.

Mathematicians struggled to find the fewest number of pieces needed to cut an equilateral triangle and rearrange it into a perfect square. The problem, known as “Dudeney’s dissection” or the ...

A geometry problem over a century old has just found its definitive answer. Mathematicians have confirmed that the solution ...