Equilateral Triangle: Classic Proof that the Sides Are Equal
This article explores Euclid’s first proposition: the construction of an equilateral triangle on a given straight line. What looks like a simple triangle is actually the first full movement of Euclidean proof. Using only a straightedge, compass and the equality created by two circles, Euclid shows how a figure can be constructed with certainty. The proof reveals how geometry moves from definition and postulate into reasoned construction, where each step follows clearly from what has already been granted.