A Glossary of Mathematical Terms - E
Edge
The line segment where two faces of a polyhedron meet.
Ellipse
One of the conic sections.
Major (longer) axis: AB;
minor (shorter) axis: CD;
vertices: A, B, C, D;
center: O:
Empty set (Null set)
The set with nothing in it.
Endpoint
A point at the end of a line segment, a vector, a ray, ... .
Enneagon (Nonagon)
A nine-side polygon.
Equation of a straight line in a cartesian coordinate system
General form: ax + by + c = 0.
Intercept form:
(x-intercept:
(p,0); y-intercept: (0,q)).
Slope-Intercept form: y = mx + q (slope:
m; y-intercept: (0,b)).
Point-Slope form: y - y1 =
m(x - x1).
Two-Points form: (x2 -
x1)(y - y1) =
(y2 - y1)(x -
x1)
Equiangular or Equilateral triangle
A triangle with all sides (and angles) congruent.
Even number
An integer number that is divisible by 2 without remainder.
Event
One or more outcomes of a probability experiment.
Exclusive "or"
One or the other, but not both.
Expanded numeral
A number written in a form which shows the value of the digits: 237 = (2x102) + (3x101) + (7X100)
Exponent (also called power)
In the expression ab (a to the power of b), b is the exponent.
Exponential function
A function of the form f(x) = ax.
Exterior angle
Used in polygons.
Extremes
In the proportion a:b = c:d, a and d. See Means.