Math Glossary Letter Rradiannouna unit of plane angular measurement that is equal to the angle at the center of a circle subtended by an arc whose length equals the radius or approximately 180°/π ~ 57.3 degrees.
radicalnounThe √ symbol that is used to denote square root or nth roots
√
radical expressionsnounan nth root of a number x is a number r which, when raised to the power n, yields x
n√x
radiusnounDistance from the center of a circle to the edge
C/2π
random numbernouna number chosen by chance
random samplingverba part of the sampling technique in which each sample has an equal probability of being chosen
random testnounselecting people for a test arbitrarily
random variablenouna variable whose value is unknown or a function that assigns values to each of an experiments outcomes
rangenounDifference between the largest and smallest values in a number set
ranknounthe data transformation in which numerical or ordinal values are replaced by their rank when the data are sorted.
rankinenounan absolute scale of thermodynamic temperature named after the University of Glasgow engineer and physicist Macquorn Rankine
ratenounthe ratio between two related quantities in different units. A measure, quantity, or frequency.
rate of returnnounthe gain or loss of an investment over a specified period of time, expressed as a percentage of the investments cost.
rationounindicates how many times one number contains another
rational exponentsnounexponents that can be expressed in the form of p/q, where q ≠ 0.
rational expressionsnounQuotient of two polynomials
P(x)/Q(x)
rational numbernouna number that can be expressed as the quotient or fraction p/q of two integers
rational root theoremnounused to find the rational solutions of a polynomial equation
rational zero theoremnounused to find the rational roots of a polynomial function
raynouna part of a line that has a fixed starting point but no endpoint
real numbernouna value of a continuous quantity that can represent a distance along a line.
reaumurnounelating to or conforming to a thermometric scale on which the boiling point of water is at 80° above the zero of the scale and the freezing point is at zero.
rebound rationounhow high the ball bounces after a static number of bounces,
Downward Distance at time n = h(1 - rr%n)/(1 - rr%)
receivablenounthe money a company's customers owe for goods or services they have received but not yet paid for.
receivables rationounmeasures the efficiency with which a company is able to collect on its receivables or the credit it extends to customers
reciprocalnouna number which when multiplied by x yields the multiplicative identity, 1
rectanglenouna quadrilateral with four right angles
rectangle word problemnouna mathematical problem expressed entirely in words involving rectangle area or perimeter typically used as an educational tool
rectangularnounA 4-sided flat shape with straight sides where all interior angles are right angles (90°).
rectangular formnounan equation composed of variables like x and y which can be graphed on a regular Cartesian plane.
rectangular solidnouna 3 dimensional object with six sides, all of which are rectangles
recursive algorithmnounan algorithm which calls itself with
smaller (or simpler) input values, and which obtains the result for the current input by applying simple operations to the returned value for the smaller (or simpler) input.
reduced digit sumnounsum all the digits until the sum < 10
reduced row echelonnouna matrix if and only if it is in row echelon form, all its pivots are equal to 1 and the pivots are the only non-zero entries of the basic columns.
reducing fractionsnoundivide both the numerator and denominator by the GCF
reference anglenounthe smallest possible angle made by the terminal side of the given angle with the x-axis.
reflectnouna flip creating a mirror image of the shape
reflexive propertynouna number is always equal to itself
a = a
regressionnouna set of statistical processes for estimating the relationships between a dependent variable and one or more independent variables.
regroupingverbmake groups of ten when performing operations such as addition or subtraction.
relative coordinatesnouncoordinates specified in relation to previous coordinates
relative errornounthe ratio of the absolute error of a measurement to the measurement being taken.
reliabilitynounthe overall consistency of a measure
remaindernounThe portion of a division operation leftover after dividing two integers
repeating decimalnouna decimal fraction in which a figure or group of figures is repeated indefinitely, as in 0.1111
repunit numbersnounnumbers that only contain 1s for digits
reservenounTo save something or set it aside for future use.
reserve rationounthe portion of reservable liabilities that commercial banks must hold onto, rather than lend out or invest
resistancenounthe property of any object or substance of resisting or opposing the flow of an electrical current.
R = V/I
resistornouna passive two-terminal electrical component that implements electrical resistance as a circuit element
resistor color codesnouncolour code used to denote the tolerance rating of a resistor is given
returnnouna performance measure used to evaluate the efficiency of an investment or compare the efficiency of several investments.
revenuenounthe money generated from normal business operations, calculated as the average sales price times the number of units sold
revolutionnounA 360° angle, a full rotation, a complete turn so it points back the same way.
rgbnounan additive color model in which the red, green, and blue primary colors of light are added together in various ways to reproduce a broad array of colors.
rhonounA letter of the greek alphabet used for math notation.
Ρ ρ
rhombusnouna quadrilateral with both pairs of opposite sides parallel and all sides the same length
right anglenounangle measuring 90 degrees
right trianglenountriangle in which one angle is a right angle
rise over runnounanother way to say slope
risknounexpose (someone or something valued) to danger, harm, or loss.
risk free ratenounthe rate of return offered by an investment that carries zero risk
roman numeralnounany of the letters representing numbers in the Roman numerical system: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000. In this system, a letter placed after another of greater value adds (thus XVI or xvi is 16), whereas a letter placed before another of greater value subtracts (thus XC or xc is 90).
rootnounValue where a function equals zero
root mean squarenounthe square root of the mean square of the set
roster notationnouna simple mathematical representation of the set in mathematical form
rot13nounsimple letter substitution cipher that replaces a letter with the 13th letter after it in the alphabet.
rotatenouna motion of a certain space that preserves at least one point.
roulettenouna gambling game in which a ball is dropped onto a revolving wheel ( roulette wheel ) with numbered compartments, the players betting on the number at which the ball will come to rest.
roundingverbreplacing a number with an approximate value that has a shorter, simpler, or more explicit representation
royal flushnouna straight flush including ace, king, queen, jack, and ten all in the same suit, which is the hand of the highest possible value when wild cards are not in use.
ruffinis rulenounan efficient method of dividing a polynomial by a linear factor, with or without a remainder.
rule of 72nouna simplified formula that calculates how long it will take for an investment to double in value, based on its rate of return.
t ~ 72/i
rule of productnounIf there are n(A) ways to do A and n(B) ways to do B, then the number of ways to do A and B is n(A) n(B)
n(A) n(B)
rule of successionnouna formula introduced in the 18th century by Pierre-Simon Laplace in the course of treating the sunrise problem
(s + 1)/(n + 2)
run length encodingverba form of lossless compression
ncG1vNJzZmivp6x7rq3ToZqepJWXv6rA2GeaqKVfoq61tIygo6iro5a%2FunrPoad4pJWpwaa%2BnIs%3D