551rational number Any number that can be
expressed as the quotient of two integersin
which the divisor is not zero. (p. 208)
ray A part of a line that has one endpoint and
goes on forever in one direction. (p. 330)
reciprocals Two numbers whose product is 1.
(p. 255)
rectangle A parallelogram with four right
angles. (p. 346)
rectangular prism A prism with six rectangular
faces. (p. 362)
rectangular pyramid A pyramid with a
rectangular base. (p. 362)
reflection A transformation that moves a figure
by flipping it along a line. (p. 356)
regular polygon A polygon with all sides and all
angles congruent. (p. 342)
regular price The original price of an item
before a discount has been given. (p. 426)
relative frequency The frequency of a category
divided by the sum of the frequencies. (p. 298)
repeating decimal A decimal in which a digit or
groups of digits repeats in an unending pattern.
(p. 206)
rhombus A parallelogram with all sides
congruent. (p. 346)
right angle An angle that measures 90°. (p. 344)
right triangle A triangle with one right angle.
(p. 344)
Roman numerals Symbols for numbers used
by the Romans. (p. 61)
rotation A transformation that moves a figure by
turning it about a fixed point. (p. 356)
rotational symmetry A figure is rotated less
than 360° around its center point and still looks
exactly the same as the original figure. (p. 358)
rounding To approximate a number by
replacing it with a number expressed in tens,
hundreds, thousands, and so on. (p. 42)
S
sale price The difference between the list price
and the discount. (p. 426)
sales tax The amount added to the marked
price of an item and collected as tax. (p. 428)
sample A segment of a population selected for
study to predict characteristics of the whole.
(p. 292)sample space A set of all possible outcomesof
an experiment. (p. 274)
scale The ratio of a pictured measure to the
actual measure; the tool used to measure
weight; numbers along the side or bottom
of a graph. (p. 308)
scale drawing A drawing of something accurate
but different in size. (p. 392)
scalene triangle A triangle with no congruent
sides. (p. 344)
scatter plot A graph with points plotted to show
a relationship between two variables. (p. 313)
scientific notation The expression of a number
as the product of a power of 10 and a number
greater than or equal to 1 but less than 10.
(p. 76)
sector A region of a circle bounded by two radii
and their intercepted arc. (p. 352)
sequence A set of numbers given in a certain
order. Each number is called a term. (p. 145)
similar figures Figures that have the same
shape. They may or may not be the same size.
(p. 388)
simple closed curve A path that begins and
ends at the same point and does not intersect
itself. (p. 342)
simple interest The amount obtained by
multiplying the principal by the annual rate by
the time (number of years). (p. 434)
simplest form The form of a fraction when the
numerator and denominator have no common
factor other than 1. (p. 188)
skew lines Lines that do not intersect, are not in
the same plane, and are not parallel. (p. 332)
solution A value of a variable that makes an
equation true. (p. 128)
sphere A curved solid figure in which all points
are the same distance from a point called
thecenter. (p. 362)
square pyramid A pyramid with a square base.
(p. 362)
square root One of two equal factors of a
number. (p. 83)
statistics The study of the collection,
interpretation, and display of data. (p. 314)8206-2_546-552 1/26/06 3:47 PM Page 551