e: Representation of the number ( 2.7182818 ...) used as the base for natural logarithms.
edge: The line segment where two faces of a polyhedron meet.
electron: A subatomic particle that carries a negative electric charge.
element: A member of a set. See also chemical element.
eliminate: To remove, to get rid of.
ellipse: The set of all points in a plane such that the sum of the distances to two fixed points is a constant.
empirical formula: A simple expression of the relative numbers of each type of atom in it, or the simplest whole number ratio of atoms of each element present in a compound.
empty set: A set that contains no elements.
endpoint: On a ray, segment, arc, or vector, a point at which the curve begins or ends; a point which touches only one other point on the curve.
equals: To be the same in value (symbol: = ).
equation: A mathematical statement that says two expressions have the same value; any number sentence with an = .
equidistant: The same distance.
equilateral: A figure containing all equal sides.
equilateral triangle: A triangle that has three equal sides.
equivalent: Two or more expressions that have the same value.
equivalent equations: Two equations with the same solutions.
equivalent fractions: Fractions that reduce to the same number.
error of measurement: The difference between an approximate measurement and the actual measure taken.
estimate: An approximate calculation of a value.
Euler's formula: A formula relating the number of vertices V , faces F and edges E of a polyhedron. Formula: V+F-E=2
evaluate: To substitute number values into an expression.
even number: A natural number that is evenly divisible by 2 .
event: In probability, a set of outcomes.
expanded notation: Method of writing numbers as the sum of powers of ten or as the sum of its units, tens, hundreds, etc.
exponent: A number that indicates the operation of repeated multiplication.
exponential function: A function in which the base e , the base of the natural logs, is raised to some power.
expression: A mathematical symbol, or combination of symbols, representing a value, or relation. Example: 2+2=4
exterior angle of a polygon: The angle outside a polygon formed by extending one of its sides.
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