In mathematics, a spherical coordinate system is a coordinate system for three-dimensional space where the position of a point is specified by three numbers: the radial distance of that point from a fixed origin, its polar angle measured from a fixed zenith direction, and the azimuthal angle of its orthogonal projection on a reference plane that passes through the origin and is …

The list of Alpha Phi Alpha (ΑΦΑ) brothers (commonly referred to as Alphas) includes initiated and honorary members. Alpha Phi Alpha is the first inter-collegiate Greek-letter organization established for Black college students. Convened in December 1905 as a literary society with the first presiding officer being CC Poindexter, it was established as a fraternity on December 4, …

Footnotes: 1 Control-C has typically been used as a "break" or "interrupt" key. 2 Control-D has been used to signal "end of file" for text typed in at the terminal on Unix / Linux systems. Windows, DOS, and older minicomputers used Control-Z for this purpose. 3 Control-G is an artifact of the days when teletypes were in use. Important messages could be signalled by striking the bell on …

El sistema de coordenadas esféricas se basa en la misma idea que las coordenadas polares y se utiliza para determinar la posición espacial de un punto mediante una distancia y dos ángulos. En consecuencia, un punto P queda representado por un conjunto de tres magnitudes: el radio, el ángulo polar o colatitud y el azimutal.. Algunos autores utilizan la latitud, en lugar de colatitud, …

A non-governmental organization (NGO) or non-governmental organisation (see spelling differences) is an organization that generally is formed independent from government. They are typically nonprofit entities, and many of them are active in humanitarianism or the social sciences; they can also include clubs and associations that provide services to their members and others.

A nucleotide is composed of three distinctive chemical sub-units: a five-carbon sugar molecule, a nucleobase (the two of which together are called a nucleoside), and one phosphate group.With all three joined, a nucleotide is also termed a "nucleoside monophosphate", "nucleoside diphosphate" or "nucleoside triphosphate", depending on how many phosphates make up the …

About half of nonmetallic elements are gases; most of the rest are shiny solids. Bromine, the only liquid, is so volatile that it is usually topped by a layer of its fumes; sulfur is the only colored solid nonmetal. The fluid nonmetals have very low densities, melting points and boiling points, and are poor conductors of heat and electricity. The solid elements have low densities, are brittle ...

Nelson Rolihlahla Mandela (/ m æ n ˈ d ɛ l ə /; Xhosa: [xolíɬaɬa mandɛ̂ːla]; 18 July 1918 – 5 December 2013) was a South African anti-apartheid activist who served as the first president of South Africa from 1994 to 1999. He was the country's first black head of state and the first elected in a fully representative democratic election. His government focused on dismantling the ...

Character reference overview. A numeric character reference refers to a character by its Universal Character Set/Unicode code point, and uses the format: &#nnnn; or &#xhhhh;. where nnnn is the code point in decimal form, and hhhh is the code point in hexadecimal form. The x must be lowercase in XML documents. The nnnn or hhhh may be any number of digits and may include …

Contents move to sidebar hide Đầu 1 Từ nguyên 2 Lịch sử Hiện/ẩn mục Lịch sử 2.1 Thời tiền sử 2.2 Thời phong kiến 2.3 Thời hiện đại 3 Địa lý Hiện/ẩn mục Địa lý 3.1 Khí hậu 3.2 Sự đa dạng sinh học 3.3 Môi trường 4 Phân cấp hành chính 5 Chính trị 6 Kinh tế Hiện/ẩn mục Kinh tế 6.1 Lịch sử kinh tế Nhật Bản ...