Area of a circle of Cnidus in the fifth century B.C. had found that the area of a disk is proportional to its radius squared. Archimedes used the tools of Euclidean geometry to show that the area inside a circle is equal to that of a right triangle whose base has the length of the circle's circumference and whose height equals the circle's radius in his book "Measurement of a Circle". The circumference is 2"r", and the area of a triangle is half the base times the height, yielding the area "r" for the disk. Prior to Archimedes, Hippocrates of Chios was the first
Planar straight-line graph Planar straight-line graph In computational geometry, a planar straight-line graph, in short "PSLG", (or "straight-line plane graph", or "plane straight-line graph") is a term used for an embedding of a planar graph in the plane such that its edges are mapped into straight line segments. Fáry's theorem (1948) states that every planar graph has this kind of embedding. In computational geometry, PSLGs have often been called planar subdivisions, with an assumption or assertion that subdivisions are polygonal. A PSLG without vertices of degree 1 defines a subdivision of the plane into polygonal regions and vice versa. The absence of vertices