> In mathematics, the number that starts as 1.618 is better known by which name?And the answer: the golden ratio.Image credit: Canva.comLike pi, the golden ratio is an irrational number thatcan be found in geometry, nature, architecture, music and more. In short, if youdivide a line into two parts, the golden ratio is found when Part B has the sameratio to Part A, as Part A does to the two combined.Often abbreviated as "phi," the golden ratio is a non-repeating number whosedecimal points span into infinity. Like pi, phi is an irrational number becauseit can not be written as the ratio of two integers. Image credit: ThoughtCo.comThe golden ratio's irrationality was first discoveredby the ancient Greek known as Euclid. As one of the founding fathers of modernmathematics, Euclid wrote a series of books called The Elements around 300 BCE.In it contained most of what was known about math at the time, and today iswidely considered one of the most influential textbooks of all time. While thename "phi" or "golden ratio" wasn't present in its pages, Euclid presented theconcept in all its novelty as the "extreme and mean ratio." Instead of thinkingof it numerically, the concept was considered in relation to the whole: theratio of the whole to the longer segment was the same as the ratio of the longersegment to the shorter line. The golden ratio appears in geometry to represent a figure whose sides are ofthis specific proportional measure. Often times, these figures are dubbed fortheir aesthetically pleasing appearance and symmetry. For example, for triangleswhose ratio of long side to short equals phi (i.e., the golden ratio), they earnthe name of "golden triangle" or "sublime triangle." The angles of the triangleare 72, 72, and 36 degrees. This golden triangle can be divided and added inpart to create similarly perfect pentagons, or a figure known as a "gnomon."Similarly, figures such as the golden rectangle can be divided again and againinto smaller golden rectangles, which, when traced, result in a perfect spiralshape. Learn more about the occurrences and use of this fascinating ratio below.