Susan Kay Fink, age 12, of Milwaukee, Wisconsin, for her question:
Who first invented and used geometry?
Our early ancestors no doubt used geometry before they knew what it was. No doubt they invented it because they needed it to solve urgent everyday problems. Certainly they needed to master the mysteries of corners to construct buildings and to measure the areas of their fields. Angled corners were partially understood before our ancestors learned to read and write. Much later, the scholars of ancient Greece used this age old experience when they invented a complete system of geometry.
The word "geometry" means "earth measuring" and it probably dates back to early farmers who used points, lines and angles to measure the area of their fields. The builders of Babylon and ancient Egypt left records of how they used simple pracitcal geometry to construct their tall terraced ziggurats and their huge tapered pyramids. The scholars of old Babylon divided the circle into 360 equal segments and used them to measure the size of angles in degrees. This was at least 5,000 years ago and the brilliant invention is still the one and only method used to measure both ordinary corners and fancy geometric angles.
Geometry remained a group of practical skills until around 600 B.C., when ancient Greece was an elegant, settled community in which scholars had time for logical thinking and reasoning. They were fond of using known facts to find unknown facts. If these items are true, they reasoned, then it follows that this also must be true. Their brilliant mathematicians used this method to establish an abstract system of geometry.
In the 600s B.C., Thales of Miletus used his knowledge of celestial angles to predict a total solar eclipse. The event came off on schedule and startled some soldiers into stopping a battle. Thales also shared his more down to earth knowledge of lines and triangles with the builders of Egypt. In the next century, the great Pythagorus created the famous therom we use to figure but relationships between sides and angles of triangles.
Other logical geniuses contributed more skills. Then came Euclid, the Greek supergenius who put it all together and invented a complete system of abstract geometry. This was around 300 B.C. Euclid kept meticulous records of his logical steps and his works survived. His books included the complete details concerning the surfaces of plane geometry, plus the forms of solid geometry. Five whole books were devoted to the complexities of solid cones. Certain practical skills were invented before his time, but certainly Euclid was the father and founder of our basic geometry system.
In 1637, the French mathematician Descartes extended Euclid's system one logical step farther. He related geometric figures and algebraic equations to invent analytic geometry. This fairly modern branch of math helped to solve the structure of atoms and to formulate the theories of relativity. A modern top notch graph maker would be lost without analytic geometry to translate complex statistics into pictureable forms.