The term diameter that concerns us now can establish that it has its etymological origin in the Greek, since it is the result of the union of several components of that language:
-The prefix "dia-", which means "through".
-The noun "metron", which can be translated as "measure".
This is called the line that, passing through the center, joins two points of a sphere, a closed curve or a circle. Also called diameter is the greater width which presents a body of circular shape.
For example: "Alarm among astronomers: an asteroid 800 meters in diameter will pass very close to our planet", "The drain will be made with a pipe two meters in diameter", "A stone two meters in diameter rolled down the mountain and crushed a vehicle".
Greek mathematician Euclid postulated, about three centuries before Christ , that the diameter of a circle is any segment that cross the center of the figure and ends, in both directions, in your circumference . That same segment, on the other hand, establishes the division of the circle into identical parts .
The relationship established between the diameter and the length of a circle is a constant known as PI number . It's about a irrational number which is usually cut in the first figures, taking as 3,14 .
Knowing the diameter of objects is important on numerous occasions. The diameter of a ring , for example, will determine whether or not this item can be placed on a finger. If the diameter is very wide, the ring will be large; on the other hand, if the diameter is very small, the ring will not enter. Of the diameter of one bottle On the other hand, it will depend on whether it is possible to store it in a certain space of the refrigerator (refrigerator) or in which part of a backpack it can be moved.
Without a doubt, one of the most interesting diameters is that of the Earth. So much so that, throughout history, there have been numerous scientists who have worked to discover it. Thus, for example, we can establish that the first to try to discover that diameter was the Greek astronomer and geographer Eratosthenes de Cyrene (276 BC - 194 BC), who used a rudimentary method to perform that measurement.
Specifically, that was based on the shadows and the summer solstice, among other aspects, which led him to conclude that the circumference of our planet was about 40,000 kilometers and the diameter was about 12,800 kilometers.
At present, we can establish that it has been established that the diameter of the Earth is about 12,756,247 kilometers, which makes it clear that the Greek astronomer cited, despite not having the technology or knowledge that we have today , made a very approximate calculation.
When talking about diameter, we can not fail to mention another term: radius. This we can establish that is half the diameter and becomes the segment that joins the center of the circle with any point of it.