Two-dimensional space

In physics and mathematics, two-dimensional space or bi-dimensional space is a geometric model of the planar projection of the physical universe. The two dimensions are commonly called length and width. Both directions lie in the same plane.

A sequence of n real numbers can be understood as a location in n-dimensional space. When n = 2, the set of all such locations is called two-dimensional space or bi-dimensional space, and usually is thought of as a Euclidean space.

History

Books I through IV and VI of Euclid's Elements dealt with two-dimensional geometry, developing such notions as similarity of shapes, the Pythagorean theorem (Proposition 47), equality of angles and areas, parallelism, the sum of the angles in a triangle, and the three cases in which triangles are "equal" (have the same area), among many other topics.

Later, the plane was described in a so-called Cartesian coordinate system, a coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates, which are the signed distances from the point to two fixed perpendicular directed lines, measured in the same unit of length. Each reference line is called a coordinate axis or just axis of the system, and the point where they meet is its origin, usually at ordered pair (0, 0). The coordinates can also be defined as the positions of the perpendicular projections of the point onto the two axes, expressed as signed distances from the origin.

Mathematical fallacy

In mathematics, certain kinds of mistaken proof are often exhibited, and sometimes collected, as illustrations of a concept of mathematical fallacy. There is a distinction between a simple mistake and a mathematical fallacy in a proof: a mistake in a proof leads to an invalid proof just in the same way, but in the best-known examples of mathematical fallacies, there is some concealment in the presentation of the proof. For example, the reason validity fails may be a division by zero that is hidden by algebraic notation. There is a striking quality of the mathematical fallacy: as typically presented, it leads not only to an absurd result, but does so in a crafty or clever way. Therefore, these fallacies, for pedagogic reasons, usually take the form of spurious proofs of obvious contradictions. Although the proofs are flawed, the errors, usually by design, are comparatively subtle, or designed to show that certain steps are conditional, and should not be applied in the cases that are the exceptions to the rules.

XY

XY or Xy may refer to:

coordinates, a system used to locate a point in two dimensions according to the cartesian coordinate system

See also

S.E.X.

"S.E.X." is the first single by Lyfe Jennings from his second album The Phoenix. The song is about young teens losing their virginity from pressure. The song features R&B singer Yolanda "La La" Brown.

"S.E.X." debuted on the Billboard Hot 100 chart at number 99 and slipped off just to re-enter the following week again at number 99. It eventually peaked at number 37, making it Lyfe's (and Lala's) most successful single. "S.E.X." was a top-five hit on the Billboard Hot R&B/Hip-Hop Songs chart and received strong airplay on BET and some airplay on radio and MTV.

References

External links

Rebel Heart (Madonna album)

Rebel Heart is the thirteenth studio album by American singer and songwriter Madonna. It was released on March 6, 2015, by Interscope Records. Following the completion of the MDNA era, Madonna worked on the album throughout 2014, co-writing and co-producing it with various musicians, including Diplo, Avicii, and Kanye West. She teased by uploading pictures of her recording sessions on her Instagram account. Working with a number of collaborators posed problem for Madonna in keeping a cohesive sound and direction for Rebel Heart, unlike her previous efforts where only a few people were involved.

Thematically Rebel Heart represents the two different sides of the singer, her romantic and her rebellious side. The themes grew organically during the writing and recording sessions. Musically, it is a pop record which merges an array of genres such as 1990s house, trap and reggae, as well as the usage of acoustic guitars and gospel choir. Some of the songs are autobiographical in nature while others talk about love and introspection of Madonna's career. Rebel Heart features guest appearances from boxer Mike Tyson and rappers Nicki Minaj, Nas, and Chance the Rapper.

S.E.X.Y.

S.E.X.Y. is an EP album by R&B-singer TQ. It was released digitally on 23 March 2009 and 30 June 2009 on Compact Disc.

Tracklist

References