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  1. en.wikipedia.org › wiki › WikipediaWikipedia - Wikipedia

    Wikipedia [c] is a free content online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki.Wikipedia is the largest and most-read reference work in history, [3] [4] and is consistently ranked among the ten most visited websites; as of August 2024, it was ranked fourth by Semrush, [5] and seventh by ...

  2. en.wikipedia.org › wiki › Solar_SystemSolar System - Wikipedia

    The Solar System[d] is the gravitationally bound system of the Sun and the objects that orbit it.[11] It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at ...

  3. In linear algebra, a rotation matrix is a transformation matrix that is used to perform a rotation in Euclidean space. For example, using the convention below, the matrix. rotates points in the xy plane counterclockwise through an angle θ about the origin of a two-dimensional Cartesian coordinate system.

  4. en.wikipedia.org › wiki › Soviet_UnionSoviet Union - Wikipedia

    t. e. The Union of Soviet Socialist Republics[ u ] (USSR), [ v ] commonly known as the Soviet Union, [ w ] was a transcontinental country that spanned much of Eurasia from 1922 to 1991. It was the largest country by area, extending across eleven time zones and sharing borders with twelve countries, and the third-most populous country.

  5. en.wikipedia.org › wiki › ChatGPTChatGPT - Wikipedia

    ChatGPT is a chatbot and virtual assistant developed by OpenAI and launched on November 30, 2022. Based on large language models (LLMs), it enables users to refine and steer a conversation towards a desired length, format, style, level of detail, and language. [2] .

  6. en.wikipedia.org › wiki › ScienceScience - Wikipedia

    Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the world. [1] [2] Modern science is typically divided into two or three major branches: [3] the natural sciences (e.g., physics, chemistry, and biology), which study the physical world; and the behavioural sciences (e.g., economics, psychology, and sociology), which ...

  7. In probability theory and statistics, a normal distribution or Gaussian distribution is a type of continuous probability distribution for a real-valued random variable.The general form of its probability density function is = (). The parameter is the mean or expectation of the distribution (and also its median and mode), while the parameter is the variance.