R

Radical   An expression such as square root..

Radius  A line segment joining any point on a circle or sphere to the center.  Also the length of that segment.

Random variable   A variable whose value is determined by the outcome of a random experiment.

Range   The difference between the greatest and the least numbers in a set of data.

Rate   A ratio that compares quantities of different kinds of units.

Ratio  0 An indicated quotient of two numbers.

Ray   A part of a line with one endpoint.

Real number   Any number that is either a rational number or an irrational number.

Reciprocals   Two numbers whose product is 1.

Rectangle  A quadrilateral with four right angles.

Rectangular prism A prism of which all the faces are rectangles

Regular polygon   A polygon in which all sides are congruent and all angles are congruent.

Reflection:            A mirror image of a figure across a line of symmetry.

Relation   A set of ordered pairs.

Relatively prime numbers Two or more numbers that have no other common factor but 1.

Remainder The last difference obtained in the division process

Repeating decimal A decimal numeral in which a digit or series of digits other than zero repeat forever in the

same pattern

Rhombus  A parallelogram in which all sides are congruent.

Right angle   An angle with measure 90°.

Right prism A solid with bases that are congruent polygons which lie in parallel planes and are perpendicular

to the lateral faces (sides) of the prism

Right triangle  A triangle with a right angle.

Rigid motions   Motions such as rotation, translation, and reflection, used to move a figure to a new position without

Roster method Defining or listing a set by naming the set with a capital letter, and naming the elements within

a pair of braces

Rounding Writing a number to a certain approximation