Glossary 337congruent triangles Two triangles are congruent if corresponding sides are congruent and
corresponding angles are congruent.
coordinate system A system that locates every point in the plane by an ordered pair of
numbers, (x, y).
corresponding angles A pair of angles that are on the same side of a transversal and are both
above or both below the parallel lines.
counting numbers The set of numbers {1, 2, 3, 4, ...} you use to count. The counting numbers
are also called the natural numbers.
cross-multiplying Finding the product of the means and the product of the extremes of a
proportion and saying that those products are equal.
cube A prism in which all the faces are squares.
cylinder A solid with two circles as parallel bases and a rectangle wrapped around to join
them.
decimal fraction Fractions written in the base ten system with digits to the right of the
decimal point.
decimal system A place value system in which each position in which a digit can be placed is
worth ten times as much as the place to its right.
denominator The number below the division bar in a fraction that tells how many parts the
whole was broken into, or what kind of fraction you have.
diameter The longest chord in a circle that passes through the center.
difference The result of a subtraction problem.
digit A single symbol that tells how many.
distributive property The distributive property says that for any three numbers a, b, and c, c(a
- b) = ca + cb. The answer you get by first adding a and b and then multiplying the sum by c will
be the same as the answer you get by multiplying a by c and b by c and then adding the results.
dividend In a division problem, the number that is divided by the divisor.
divisor In a division problem, the number you divide by.
equation A mathematical sentence, which often contains a variable.
equiangular triangle A triangle in which all three angles are 60°.
equilateral triangle A triangle in which all three sides are the same length.