# Mathematical Dictionary - Letter S

CONICAL SECTIONS - Curves obtained by intersecting a conical surface by a plane. According to the position of the plane this is obtained: point, circumference, ellipse, parable, hyperbole.

STRAIGHT SEGMENT - Part of a line limited between two points.

SECONDS - Time unit translated by seconds = 1 minute. We also call second unit angles.

WEEK - Space of seven days. The word week derives from septum (seven and mane (morning or day).

SIMILAR - Two figures are said to be similar if both are congruent or one is an enlargement or reduction of the other.

SEMICIRCLE - Half a circle, ie one of the parts of the circle delimited by the diameter.

SENO (Sen) - In a right triangle the sen A (acute angle) is quotient between the opposite side of this angle and the hypotenuse.

SENTENCE OF A FUNCTION - its definition expressed through variables. Ex: f (x) = 3x + 5.

SEPTEMBER - That is worth seven times another, or seven times greater than another.

SEPTUPLICATE - Make it seven times bigger. Multiply by seven.

SEPTENATE - Name by which the government of France, established in 1873 and lasting seven years, became known.

SEQUENCE - Numbers or geometric figures arranged in a certain order. 1, 3, 5, 7,… is the sequence of odd numbers, for example.

SEPTEMBER - In the Roman calendar was September the seventh month of the year. In the Muslim calendar the seventh month corresponding to Ramadan, that is, the month of Lent.

SEXAGESIMAL - Unit using base 60. As with angle measurement where a degree is 60 minutes and a minute is 60 seconds.

SYMBOL - Graphic sign that represents a mathematical idea. Numbers are written with symbols called ALGARISM.

SYMMETRICAL - A figure in one, two or three dimensions is said to be symmetrical if it has a symmetry element (point, axis or plane), so that on the other side of this symmetry element the figure is similar but inverted, as if it had been placed in front of a mirror.

SIGNALS - There are several signs that are used in mathematical writing, such as the signs of operations and the digits themselves. To compare numbers the signs are used:> (greater than), <(less than), (other than), = (same as)

BINARY SYSTEM - It is a numbering system that uses two digits (0 and 1) to represent quantities. This is the system used by computers because we need two digits to represent the two situations (on or off) that occur on their internal electronic circuits.

DECIMAL SYSTEM - It is a numbering system that uses ten digits to represent quantities. Ex .: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

HEXADECIMAL SYSTEM - It is a numbering system that uses sixteen digits to represent quantities. Eg: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. It is usually linked to computer science because computers interpret programming languages ​​in bytes, which are made up of eight digits.

OCTAL SYSTEM - It is a numbering system that uses eight digits to represent quantities. Eg 0, 1, 2, 3, 4, 5, 6, 7. It is an 8-bit processor time system. Currently this type of notation is hardly used.

EQUATION SYSTEM - Set of equations with the same variables and with the same roots.

SOLID - A figure in three dimensions. Examples of solids are: cube, parallelepiped, pyramid.

SUM One of the main basic operations of arithmetic, which results in the addition of numbers.

SUMMARY - Synthetic way of indicating an addition of different plots. The symbol used is a capital sigma. Example: This nomenclature is the same as writing the sum of powers of 2 whose exponents range from 1 to 5, ie 2 + 4 + 8 + 16 + 32.

SUBSET - Rumor has it THE is a subset of B if all the elements of THE belong to B.

REPLACEMENT - Method of solving a system of equations which consists of determining in one of them the value of an unknown and substituting the unknown value in the remaining equations.

SUBTRACTION - One of the four basic operations of arithmetic, which aims to remove one number from another. It is an artificial operation created from the addition.

SUCCESSION - Set of objects presented in a certain sequence. Example: What is the next number of successions: 1, 2, 3, 4… and 7, 14, 21, 28, 35… Are 5 and 42 respectively.

FIBONACCI SUCCESSION - An infinite succession where each term is obtained by adding the previous two. In nature it often appears, for example in the distribution of the "petals" of a pine cone. Example: 1, 1, 2, 3, 5, 8, 13, 21…

SURFACE - A smooth two-dimensional geometric entity (which has no beaks) and has an area measure, that is, a region that can be flattened (placed on a plane) so that the new flat region has the area equivalent to that of a square.

CYLINDRICAL SURFACE - Surface generated by a line (generatrix) that runs parallel to itself and supported by a curve (guideline).

CONIC SURFACE - Surface generated by a line (generatrix) that moves supported by a curve (guideline) maintaining a fixed point (vertex).

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