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Plot of Si(x) for 0 ≤ x ≤ 8π. Plot of the cosine integral function Ci(z) in the complex plane from −2 − 2i to 2 + 2i. The different sine integral definitions are = = .
The curie (symbol Ci) is a non-SI unit of radioactivity originally defined in 1910. According to a notice in Nature at the time, it was to be named in honour of Pierre Curie , [ 1 ] but was considered at least by some to be in honour of Marie Curie as well, [ 2 ] and is in later literature considered to be named for both.
A formula for computing the trigonometric identities for the one-third angle exists, but it requires finding the zeroes of the cubic equation 4x 3 − 3x + d = 0, where is the value of the cosine function at the one-third angle and d is the known value of the cosine function at the full angle.
The older, non-SI unit of activity is the curie (Ci), which is 3.7 × 10 10 radioactive decays per second. Another unit of activity is the rutherford, which is defined as 1 × 10 6 radioactive decays per second.
The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science ...
The becquerel succeeded the curie (Ci), [12] an older, non-SI unit of radioactivity based on the activity of 1 gram of radium-226. The curie is defined as 3.7 × 10 10 s −1, or 37 GBq. [4] [13] Conversion factors: 1 Ci = 3.7 × 10 10 Bq = 37 GBq; 1 μCi = 37 000 Bq = 37 kBq; 1 Bq = 2.7 × 10 −11 Ci = 2.7 × 10 −5 μCi; 1 MBq = 0.027 mCi
cis is a mathematical notation defined by cis x = cos x + i sin x, [nb 1] where cos is the cosine function, i is the imaginary unit and sin is the sine function. x is the argument of the complex number (angle between line to point and x-axis in polar form).
The SI base units form a set of mutually independent dimensions as required by dimensional analysis commonly employed in science and technology. [ citation needed ] The names and symbols of SI base units are written in lowercase, except the symbols of those named after a person, which are written with an initial capital letter.