A Glossary of Mathematical Terms - I
Icosahedron
A 20-sided solid;, each face is in the shape of a triangle.
Identity element
In operations (addition, multiplication, ...) the element that is neitral as far as the outcome is concerned.
Iff
If and only if.
Imaginary number
A complex number with no real part.
Improper fraction
See fraction.
Improper subset
The null subset of a set or the whole set as a subset.
Integer
A member of the set {0, +1, -1, +2, -2, ... }.
Intercept
The point where a curve meets the x-axis (x-intercept) or the y-axis (y-intercept).
Interior angles
Usually referred to the angles of a polygon.
Intersection of sets
The set consisting of all elements that are common to two or more sets.
Interval
The set of all real (rational) numbers betwenn two fixed real (rational) numbers.
Isometry
A tarnsformation that keeps the same size and shape of figures.
Isosceles
A polygon with two sides equal in length. Usually referred to triangles and trapezoids.