# Math Dictionary i

I

Icosahedron : A polyhedron having twenty faces. A regular icosahedron is one of the five Platonic solids and has twenty equilateral triangles as faces.

Identity elements: For a binary operation * and a set S, Ι is the identity element if a * Ι = a and Ι * a = a for every element a that is in S.

Image: The resulting point or set of points under a given transformation; in any function f , the image of x is the functional value f (x) corresponding to x .

Improper fraction : An improper fraction is a fraction where the numerator (the top number) is greater than or equal to the denominator (the bottom number). In other words, it is top-heavy.

Inch : An inch is a measure of length. There are 12 inches in a foot, and 36 inches in a yard.

Incenter of a triangle: The center of the circle that is inscribed in a triangle; the point of concurrence of the three angle bisectors of the triangle which is equidistant from the sides of the triangle.

Included angle: The interior angle formed by two sides of a polygon.

Included side: The side between two consecutive angles in a polygon.

Independent Event : An outcome that is not affected by previous outcomes.

Indirect proof: A method of proof in which the statement that is to be proven is assumed false and a contradiction results.
Inductive reasoning: The process of observing data, recognizing patterns and making generalizations about those patterns.

Inequality : An inequality says that two values are not equal.a ≠ b says that a is not equal to b.
There are other special symbols that show in what way things are not equal.
a < b says that a is less than b
a > b says that a is greater than b
(those two are known as strict inequality)
a ≤ b means that a is less than or equal to b
a ≥ b means that a is greater than or equal to b.

Inscribed angle: An angle whose vertex lies on the circle and whose sides are chords of a circle.

Inscribed circle: A circle in the interior of a polygon that is tangent to each side of the polygon.

Intercepted arc: An arc of a circle whose endpoints lie on the sides of an angle, and all of the points on the arc are in the interior of the angle.

Infinite : Without an end. Not finite.

Infinity: An idea that something never ends. It is sometimes used like a number but it is not really. The symbol is ∞.(

Inradius : Another name of Apothem.

Integer : ncludes the counting numbers {1, 2, 3, ...}, zero {0}, and the negative of the counting numbers {-1, -2, -3, ...}

Interior: The set of all points inside a geometric figure.

Interest : Money paid for the use of other money.

Intersecting lines: Lines that share a common point.

Intersection of sets: The intersection of two or more sets is the set of all elements that are common to all of the given sets.

Invariant: A figure or property that remains unchanged under a transformation of the plane.

Inverse of a statement: A statement formed by negating both the hypothesis and conclusion of a given conditional.

Irrational numbers : An Irrational Number is a real number that cannot be written as a simple fraction.(math dictionary i)

Isometry : A transformation of the plane that preserves distance.

Isosceles trapezoid: A trapezoid in which the non-parallel sides are congruent.

Isosceles triangle : A triangle that has at least two congruent sides.

math dictionary i

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