Eratosthenes (c. 276 – 194 BC) was born more than 2200 years ago in the Greek city of Cyrene, now a city in the North African country of Libya. (The Greek Empire surrounded much of the Mediterranean ... Continue reading
Originally, each country had its own, and rather poorly reproducible, unit of luminous intensity; it was necessary to wait until 1909 to see a beginning of unification on the international level, when ... Continue reading
Pythagoras was a famous Greek mathematician. He was particularly interested in the properties of triangles, and discovered a simple, fundamental relationship between the lengths of the sides of right ... Continue reading
The cone is another three-dimensional shape based on the circle. You could think of it as the cross between a circle and a right triangle. Its properties will have features of both shapes, and this ... Continue reading
