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Since C = 2πr, the circumference of a unit circle is 2π. In mathematics, a unit circle is a circle of unit radius—that is, a radius of 1. [1] Frequently, especially in trigonometry, the unit circle is the circle of radius 1 centered at the origin (0, 0) in the Cartesian coordinate system in the Euclidean plane.
The design of most cross and circle games involves a circle divided into four equal portions by a cross inscribed inside it; the classic example of this design is the Korean game Yut. However, the term "cross and circle" is typically widened to include boards that replace the circle with a square, and cruciform boards that collapse the circle ...
Cross and circle boards may suggest a variety of mystical, symbolic, or esoteric designs such as mandalas; sun and earth symbols; swastikas; or Celtic, Coptic, and Greek crosses. However, mere visual similarities do not prove a deeper connection; and demonstrating any historical connection has proven to be a slippery matter.
The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. It is defined such that one radian is the angle subtended at the centre of a circle by an arc that is equal in length to the radius. [ 2 ]
[18] [19] Today, the degree, 1 / 360 of a turn, or the mathematically more convenient radian, 1 / 2 π of a turn (used in the SI system of units) is generally used instead. In the 1970s – 1990s, most scientific calculators offered the gon (gradian), as well as radians and degrees, for their trigonometric functions. [23]
English: Some common angles (multiples of 30 and 45 degrees) and the corresponding sine and cosine values shown on the Unit circle.The angles (θ) are given in degrees and radians, together with the corresponding intersection point on the unit circle, (cos θ, sin θ).
"current": AC (for "alternating current"); less commonly, DC (for "direct current"); or even I (the symbol used in physics and electronics) Roman numerals: for example the word "six" in the clue might be used to indicate the letters VI; The name of a chemical element may be used to signify its symbol; e.g., W for tungsten
The magnitude of an object's solid angle in steradians is equal to the area of the segment of a unit sphere, centered at the apex, that the object covers. Giving the area of a segment of a unit sphere in steradians is analogous to giving the length of an arc of a unit circle in radians. Just as the magnitude of a plane angle in radians at the ...