Scalar - A non-dimensional quantity. A scale factor. A multiplier. See coefficient.

Scale - .

Scalene triangle - A triangle with every side of different length.

Secant of a circle - A line passing through two points of a circle. See diameter, chord, tangent of a circle.

Secant of an Angle - In a right triangle, for a given angle, the ratio of the length of the hypotenuse adjacent leg (the side next to the measured angle. In an expression, abbreviated "sec." See trigonometric function.

Sector - .

Seed - The value used to start a number pattern or sequence. The value does not necessarily appear in the sequence itself. For example, a hidden value may be used to control the starting point of a random number generator.

Segment - See line segment or arc segment.

Semicircle - Half of a circle. Its central angle and included arc both measure 180 degrees.

Set - A list. Identical elements are generally listed only once. It is usually convenient to place the elements in some kind of definable order. See union and intersection, empty set.

Side - A segment which forms one part of the perimeter of a polygon.

Sieve of Eratosthenes - A method of finding prime numbers (which have no factors) by eliminating the composite numbers (which have factors) from a list of positive whole numbers (natural numbers) which begins with 2.
Method: Circle the least remaining value on the list, then cross out all the available multiples of that number by multiplying, adding or counting. Repeat for the next-lower remaining number. Efficient use can be made of a printed table which has ten numbers to a line but with the "1" position blank so that each line ends with a multiple of 10. Patterns will emerge which will considerably speed up the process. See the explanation on Sieve of Eratosthenes.

Sign - A symbol placed before a numeral to signify whether that numeral is positive or negative. An unsigned, nonzero number is generally considered to be positive. See absolute value.

Similar - Having the same shape but not necessarily the same size. All corresponding angles are congruent. All corresponding segments are proportional.

Simplify - .

Sine - In a right triangle, for a given angle, the ratio of the length of the opposite leg divided by the length of the hypotenuse. In an expression, abbreviated as "sin." See trigonometric function.

Size - .

Skew - Neither parallel nor perpendicular.

Slant height - .

Slope - .

Solution - .

Solution set - .

Solve - .

Space - The set of all points, usually implied to refer to three physical dimensions.

Sphere - A closed, curved surface with every point on the surface equidistant from the center. See locus, circle.

Square - A polygon with four congruent sides and four congruent angles. A regular quadrilateral. An equilateral rectangle. An equiangular rhombus. The union of four line segments with each endpoint intersecting exactly one other endpoint so that intersecting segments are perpendicular. The perimeter of a square is four times the length of a side. The area is the square of a side.

Square root - The number which multiplied by itself equals the original number. The inverse operation of squaring a number. The half-power of a number. See the explanation on finding Square Root.

Square unit - .

Standard form of a polynomial - A polynomial in one variable with powers in descending order. The general form for a second order polynomial is ax²+bx+c.

Statement - .

Step - .

Substitution - .

Subtraction - A shortcut for counting down from one number to another in order to find the difference between the two numbers (remainder). The inverse or opposite of addition. The arithmetic can be checked by addition.

Sum - The result of an addition operation. Total.

Summation - .

Supplementary - .

Surface - A contiguous set of points in space containing no vertices, edges or intersections (the surface may be bounded by any of the preceeding figures. A flat or curved, smooth, three-dimensional figure with no edges (folds, creases or corners) running through it.

Symmetry - .

Last updated 6/2/97 - 5/3/2000.