What's in a word
Etymology: The Indo-European root ank- or ang-, 'to bend' gives rise to various words referring to bent or bendable things, including ankle, and England (Angle-land, Anglia, from the shape of the original homeland, the Angul district of Schleswig, of the people who came to be known as the "Angles.")
Other related words: ankle, angle (in the fishing sense, from the obsolete use to mean 'fishhook'), England, anchor.
Sum of interior angles in a quadrilateral
Related mathematical terms
Triangle, Rectangle, Equiangular