Mathematics Class IX (Telangana SCERT) Terminology

This vocabulary deck covers fundamental mathematical concepts from the Class IX textbook, including number systems, algebra, geometry, coordinate geometry, statistics, and probability.

Natural Numbers

The set of positive counting numbers, typically denoted as N = {1, 2, 3, …}.

Integers

The collection of whole numbers and their negatives, denoted by Z or I = {… -3, -2, -1, 0, 1, 2, 3, …}.

Rational Number

A number that can be expressed in the form \frac{p}{q} where p and q are integers and q \neq 0. They appear as terminating or non-terminating recurring decimals.

Irrational Number

A number that cannot be written in the form \frac{p}{q}. Its decimal expansion is non-terminating and non-recurring (e.g., \sqrt{2}, \pi).

Polynomial

An algebraic expression in which the variables involved have only non-negative integral powers (e.g., x^2 + 2x + 1).

Degree of a Polynomial

The largest degree of its variable terms; the highest exponent of the variable in the expression.

Linear Equation in Two Variables

An equation that can be expressed in the form ax + by + c = 0, where a, b, c are real numbers and the graph is a straight line.

Axiom

A mathematical statement assumed to be self-evident and true without requiring proof.

Postulate

A term used for assumptions specifically made in the context of geometry.

Complementary Angles

A pair of angles whose measures sum to exactly 90^{\circ}.

Supplementary Angles

A pair of angles whose measures sum up to 180^{\circ}.

Transversal

A line that intersects two or more distinct lines at distinct points.

Congruent Figures

Figures that are identical in both shape and size; if placed on top of each other, they cover exactly.

Abscissa

The x-coordinate of a point in a Cartesian plane, representing its distance from the y-axis.

Ordinate

The y-coordinate of a point in a Cartesian plane, representing its distance from the x-axis.

Parallelogram

A quadrilateral in which both pairs of opposite sides are parallel.

Midpoint Theorem

The line segment joining the midpoints of two sides of a triangle is parallel to the third side and half its length.

Mean (Arithmetic Mean)

The sum of observations divided by the total number of observations, denoted as \bar{x} = \frac{\sum x_i}{n}.

Median

The middle-most value of a data set when the observations are arranged in ascending or descending order.

Mode

The observation that occurs most frequently in a data set.

Right Circular Cylinder

A solid with a curved surface and two congruent circular bases where the segment joining the centers is perpendicular to the bases.

Probability of an Event

The ratio of the number of favorable outcomes to the total number of possible outcomes: P(A) = \frac{\text{Favorable outcomes}}{\text{Total possible outcomes}}.

Cyclic Quadrilateral

A quadrilateral whose four vertices lie on the circumference of a single circle.

Deductive Reasoning

The process of arriving at a logical conclusion from previously established statements or truths.