Eighth Grade Math Vocabulary

Adjacent Angles that have a common vertex and a common side Examples 3 4 <1 and <2 are adjacent <3 and <4 are adjacent 5 6 <5 and <6 are adjacent

Alternate Exterior Angles A pair of angles on the outer sides of two lines cut by a transversal, but on opposite sides of the transversal Examples <1 and <8 are alternate exterior <2 and <7 are alternate exterior

Alternate Interior Angles A pair of angles on the inner sides of two lines cut by a transversal, but on opposite sides of the transversal Examples <3 and <6 are alternate interior <4 and <5 are alternate interior

Complementary Two angles whose measures have a sum of 90° Examples <1 and <2 are complementary = <1 + <2 = 90 Complementary

Corresponding Angles that are on the same side of the transversal and are both above or both below the lines cut by the transversal Examples <3 and <7 are corresponding <1 and <5 are corresponding <2 and <6 are corresponding <4 and <8 are corresponding

Cost per unit A unit rate used to compare costs per single item A rate in which the second quantity is one Examples If a 12-pack of coke costs $2.76 One coke costs $0.23 If 20 ounces of bottled water costs $1.00 (100 cents) then one ounce costs 5 cents If a pack of 10 markers costs $3.90, one marker costs $0.39

Dilation A transformation that enlarges or reduces a figure by some scale factor, but does not change its shape Examples Each side of the blue triangle Is half the length of the side of the red triangle The large tree is Four times as Tall and wide As the small tree

Distance Formula Examples The distance between (-3,2) and (0,-2) is: (-3,2) (0,-2) The distance d between any two points and is

Distributive Property The property which states that multiplying a sum by a number gives the same result as multiplying each addend by the number and then adding the products a (b + c) = a x b + a x c Examples

Experimental Probability The ratio of the number of times the event actually occurs to the total number of trials or times the activity is performed (The theoretical probability would predict how many times the event should occur) Example A coin is tossed 50 times with a result of 27 heads and 23 tails. The experimental probability of heads is or 54%. (The theoretical probability of heads is or 50%)

Exterior The angles on the outer sides of two lines cut by a transversal Examples ( <3, <4, <5 and <6 are interior angles) <1, <2, <7 and <8 are exterior angles

Infinite Having no end or limit, without bound, uncountable Examples The set has an infinite number of elements is the symbol for infinity The set has an infinite number of elements The number of points on a line is infinite

Intercept The point where a graph crosses the axis The y-intercept of the line y = mx+b is b Example y-intercept:3 x-intercept:-1 y=3x+3 y x

Interior Angles on the inner sides of two lines cut by a transversal Example ( <1, <2, <7 and <8 are exterior angles) <3, <4, <5 and <6 are interior angles

Line of best fit (conceptual) A straight line that best fits the data on a scatter plot (This line may pass through some, none, or all of the points) Examples

Nonlinear equation A function whose graph is not a straight line Examples

Perfect Square A number that has integers as its square roots Examples

Pythagorean Theorem In a right triangle, the sum of the squares of the length of the legs is equal to the square of the length of the hypotenuse :

Scientific notation A method of writing very large or very small numbers by using powers of 10 Examples The Andromeda Galaxy contains at least 200,000,000,000 or 2.0 X stars The diameter of an atom of gold is about or 2.5X10 -9 inches

Sequences An ordered list of numbers or objects called terms Examples Arithmetic Sequence: The difference between any two consecutive terms is always the same: 5,8,11,14,17,20,… The common difference is 3 Geometric Sequence: The ratio of any two consecutive terms is always the same: 5,10,20,40,80,160,… The common ratio is 2

Slope intercept form A linear equation written in the form Where m represents slope and b represents the y-intercept Examples: slope = -1 y-int = 2 slope = 1 y-int = -3 slope = 2 y-int = -3

Square root One of the two equal factors of a number Examples and (6 and -6)

Supplementary Two angles whose measures have a sum of 180° Two adjacent angles whose exterior sides form a straight line Examples

Theoretical probability The ratio of the number of equally likely outcomes in an event to the total number of possible outcomes A number used to describe the chance of an event occurring Examples The probability of rolling an even number on a six-sided number cube is 3/6 or ½ or 50%: There are three even numbers (2,4,6) out of six possible outcomes (1,2,3,4,5,6) What is the probability that if you randomly choose a letter in the word Tennessee You will choose an e? You can choose 4 e’s out of 9 letters 4/9 or about 44.4% Tennessee

Vertical Angles A pair of opposite congruent angles formed by intersecting lines Examples Angles 1 and 2 are vertical Angles 3 and 4 are vertical The two angles are vertical

Vertical Line test A way of testing a graphed relation to determine if it is a function: “If a vertical line passes through more than one point on the graph, then the relation is not a function” Examples Each vertical line passes Through only one point, So, y=x 2 is a function Vertical lines pass through more than one point, So, x 2 + y 2 =9 is not a function