342 Appendix C
regular polygon A polygon is regular if all sides are the same length and all angles are
congruent.
relatively prime Two numbers are relatively prime if the only factor they have in common is 1.
remainder The number left over at the end of a division problem. It’s the difference between
the dividend and the product of the divisor and quotient.
rhombus A parallelogram in which all sides are congruent. A square is a parallelogram with
four congruent sides and four right angles.
right angle An angle that measures 90s.
right prism A prism is a right prism if the parallelograms meet the bases at right angles.
right triangle A triangle that contains one right angle.
ruler A line or segment divided into sections of equal size, labeled with numbers, called
coordinates, used to measure the length of a line segment.
scale factor The scale factor of two similar triangles is the ratio of a pair of corresponding
sides.
scalene triangle A triangle that has three sides of different lengths.
scientific notation A method for expressing very large or very small numbers as the product
of a number between 1 and 10 and a power of 10.
secant A line that intersects the circle at two different points.
segment bisector A line or ray or segment that passes through the midpoint of a segment and
divides a segment into two congruent segments.
semicircle An arc equal to half a circle.
sides of angle The rays with a common endpoint that form the angle.
similar triangles Two triangles are similar if each pair of corresponding angles is congruent
and corresponding sides are in proportion.
slope The slope of a line is a number that compares the rise or fall of a line to its horizontal
movement.
solving an equation An equation is a mathematical sentence that often contains a variable.
Solving an equation is a process of isolating the variable to find the value that can replace the
variable to make a true statement.
space The set of all points.
sphere The set of all points in space at a fixed distance from a center point.