E

Edge (of polyhedron) A line segment formed by the intersection of two faces of a polyhedron

Edge (of prism) A line segment formed by the intersection of two faces of a prism

Element A member of a set

Empty set The set with no elements, represented by 0. (Some mathematicians also use f I to represent the empty set.)

Endpoint   The point at the end of a line segment or ray.

Equality (of fractions) Two fractions,         a

Equation   A mathematical sentence with an equals sign to indicate that two expressions name the same number.

Equiangular A polygon with equal angles. (Regular polygon).

Equilateral triangle  A triangle in which all sides are congruent.

Equivalent equations   Equations that have the same solution.

Equivalent fractions Fractions that name the same number.

Equivalent inequalities   Inequalities that have the same solutions.

Estimate A guess made as the answer to a problem by using numbers which are close in value to the numbers

used in the problem)

Evaluate an expression   To replace a variable in an expression with one of its values and then complete the

indicated arithmetic.

Event A specific outcome or type of outcome.

Exact number The number used to express a count of objects (308)

Expanded form   The method of representing a number as the sum of products of each digit and powers of 0.

Expanded notation Writing a number as an indicated sum of face values times place values (13)

Expected value The average value that one would expect to get over many attempts.

Experimental probability An estimated probability based on the relative frequency of positive outcomes                      

occurring during an experiment.

Exponent A number indicating how many times the base is used as a factor. In 54, the exponent is 4.

Exterior angle If the a side of a polygon is extended, an exterior angle is formed.

Extremes of a proportion  0 The first and last terms of a proportion.

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