e : The number "e" is one of the most important numbers in mathematics. The first few digits are: 2.7182818284590452353602874713527 (and more ...)
It is often called Euler's number after Leonhard Euler.
Eccentricity : How much a "conic section" (a circle, ellipse, parabola or hyperbola) varies from being circular. Example: A circle has an eccentricity of zero.
Edge of a polyhedron: : A line segment that connects two consecutive vertices of a polyhedron.
Element : A member of a set.
Ellipse: A set of points 1 P in a plane, such that the sum of the distances from P to two fixed points 1 F and 2 F is a given constant k . Any plane section of a circular conical surface which is a closed curve.
Endpoint: A point at either the end of a line segment, or arc, or the initial point of a ray.
Equal Chords : Two chords which are equidistant from the center are called equal chords.
Equiangular : A polygon with all interior angles congruent.
Equation :An equation says that two things are the same, using mathematical symbols.
Equidistant : At the same distance.
Equilateral polygon: A polygon with all sides congruent.
Equilateral triangle : A triangle with three congruent sides.
Equinox : The time of the year when day and night are each 12 hours long and the Sun is at the midpoint of the sky.This happens twice a year:
* Spring equinox
* Autumn (Fall) equinox
Equivalence relation: A relation that exhibits the reflexive, symmetric, and transitive properties.
Equivalent fraction : Fractions which have the same value, even though they may look different.
Example 1/2 and 2/4 are equivalent, because they are both "half".
Estimation : Finding a value that is close enough to the right answer, usually with some thought or calculation involved.
Euclidean Geometry: The study of geometry based on definitions undefined terms (point, line and plane) and the assumptions of Euclid (c.a. 330 B.C.)
Euclidean Parallel Postulate: Any assumption equivalent to the following statement: If l is any line and P is any point not on l , then there exists exactly one line through P that is parallel to l .
Euler line: For any given triangle, the line that contains the circumcenter, the centroid and the orthocenter.
Even number: Any integer that can be divided exactly by 2.
The last digit will be 0, 2, 4, 6 or 8
Exponent : The exponent of a number shows you how many times the number is to be used in a multiplication.
Expression :Numbers, symbols and operators (such as + and ×) grouped together that show the value of something.
External segment of a secant : If a secant is drawn to a circle from an external point, the portion of the secant that lies outside the circle.
Exterior of a geometric figure: The set of all points outside a geometric figure.
Exterior angle of a polygon: An angle formed by a side of a polygon and the extension of an adjacent side. Math dictionary e