The golden ratio

The Golden Rectangle is a remarkable shape and is very pleasing to the eye.

Euclid's Elements provides the first known written definition of what is now called the golden ratio: "A staight line is said to have been cut in extreme and mean ratio when, as the whole line is to the greater segment, so is the greater to the less." A construction for cutting a line in extreme and mean ratio is the golden ratio.

Allison Mumford, Created with GeoGebra