Delta is the name of the fourth letter of the Greek alphabet (\u0394, \u03b4), equivalent to the Latin \u00abD, d\u00bb. It was derived from the Phoenician letter \u201cdaleth\u201d, \u201cthe door\u201d.<\/b><\/p>\n
\n\tWe call also "delta<\/em>" the mouth of some rivers, because the precipitation of sediments transported by various arms make precisely a triangular shaped landform. In antiquity the most famous delta <\/em>is this of the Nile River<\/em>, about which Herodotus <\/em>(lived between 484-425) speaks repeatedly, for example in his book II <\/em> considering it a alluvial product.<\/p>\n \n\tHerodotus <\/em>is the author of the famous phrase "(Egypt) is a gift of the Nile; δ\u1ff6ρον το\u1fe6 ποταμο\u1fe6 (Histories, II, 5.1)”<\/strong><\/em><\/p>\n \n\tThe old gégografos as Strabo <\/em>or Pomponius Mela <\/em>refer to this mouth as "The Delta<\/em>". Later the name has been widely used as a technical term in river geography.<\/p>\n \n\tDelta <\/em>is also the modern instrument triangular shaped wing (delta wing, hang gliding<\/em>) that allows some people to realize the old intrepid human desire to fly like Daedalus<\/em>. The characteristics of the materials, lighter and stronger, allowing these people to ascend to great heights, move to distant places taking advantage of the air currents, sustained for hours in the air and land with the necessary finesse to avoid (not always) accidents.<\/p>\n \n\t"Deltoid<\/em>" is called man shoulder muscle precisely because it is shaped like the Greek letter.<\/p>\n \n\tAs mathematical symbol<\/em> the letter δ <\/strong>is used to indicate the change of a function with respect to one of the variables that describe the function itself. Δ <\/strong>is also commonly used in Physics <\/em>to represent the Dirac delta function.<\/em><\/p>\n \n\tThe uppercase Δ <\/strong>represents the Laplacian operator<\/em> introduced by Laplace <\/em>in his study of partial differential equations.<\/p>\n \n\tBoth uppercase and lowercase letter delta Δ, δ <\/strong>plays an important role in describing important Physical theories as the equations of Maxwell<\/em>’s electromagnetism , the wave equation of quantum mechanics or gravitation theory of Einstein<\/em>.<\/p>\n \n\tThe lowercase letter delta δ <\/strong>is used in Astronomy <\/em>to indicate the position, along with the letter alpha <\/em>α, of the stars in the sky. Two angles are needed (right ascension and declination) to define the position of the stars and other objects in the sky. The right ascension is denoted by alpha and delta declination (both lowercase).<\/p>\n \n\tDelta <\/em>is also the euphemistic name with which the Greeks referred to female genitals<\/em>, the pubic triangle that in adolescence is covered with hair. Later they used the name " mons Veneris = Hill of Venus<\/em>" and "mons pubis = pubic bush<\/em>" to designate the same part of the female body.<\/p>\n \n\tFor example, in the comedy of Aristophanes Lysistrata, 151<\/em> "the convincing Greek wife" says:<\/p>\n \n\tLYSISTRATA \n\tΠολ\u1f7b γε ν\u1f74 τ\u1f7c θε\u1f7d.
\n\tBy the two Goddesses, now can't you see
\n\tAll we have to do is idly sit indoors
\n\tWith smooth roses powdered on our cheeks,
\n\tOur bodies burning naked through the folds
\n\tOf shining Amorgos' silk, and meet the men
\n\tWith our dear Venus-plats plucked trim and neat.
\n\tTheir stirring love will rise up furiously,
\n\tThey'll beg our arms to open. That's our time!
\n\tWe'll disregard their knocking, beat them off—
\n\tAnd they will soon be rabid for a Peace.
\n\tI'm sure of it. <\/strong><\/em> (Jack Lindsay, Ed. )<\/p>\n
\n\tΕ\u1f30 γ\u1f70ρ καθ\u1fc4μεθ\u1fbf \u1f14νδον \u1f10ντετριμμ\u1f73ναι,
\n\tΚ\u1f70ν το\u1fd6ς χιτων\u1f77οισι το\u1fd6ς\u1fbfΑμοργ\u1f77ονις
\n\tγυμνα\u1f76 παρ\u1f77οιμεν δ\u1f73λτα παρατετιλμ\u1f73ναι,
\n\tστ\u1f7bοιντο δ\u1fbf\u1f04νδρες κ\u1f00πιθυμο\u1fd6εν σπλεκο\u1fe6ν,
\n\t\u1f21με\u1fd6ς δ\u1f72 μ\u1f74 προσιε\u1f77μεθ\u1fbf, \u1f00λλ\u1fbf \u1f00πεχο\u1f77μεθα,
\n\tσπονδ\u1f70ς πο\u1f75σαιντ\u1fbf \u1f02ν ταχ\u1f73ως, ε\u1f56 ο\u1f36δ\u1fbf \u1f45τι.<\/p>\n