Grade 9 Mathematics Flashcards

Vocabulary flashcards covering geometry basic concepts, relations and functions, parallelograms and special quadrilaterals, slopes and zeros of linear functions, and conditions for parallelism and perpendicularity.

Point

An undefined term in geometry that indicates a specific location in space and has no size, width, length, or depth.

Line

An undefined term in geometry described as a one-dimensional straight path that extends infinitely in two opposite directions.

Plane

An undefined term in geometry described as a two-dimensional flat surface that extends infinitely in all directions along its surface.

Line Segment

A subset of a line consisting of two endpoints and all the points in between, which has a measurable length.

Ray

A subset of a line that starts at one endpoint and extends infinitely in one direction.

Angle

A geometric figure formed by two rays that share a common endpoint called the vertex.

Vertex

The common endpoint shared by the two rays that form an angle.

Sides of an Angle

The two rays that share a common endpoint to form an angle.

Relation

A pairing, connection, or relationship between two quantities or objects.

Function

A special type of relation where each input has exactly one output.

Domain

The set of all possible input values of a relation or function, usually representing the $x$-values.

Range

The set of all possible output values of a relation or function, usually representing the $y$-values.

Vertical Line Test

A method used to determine if a graph represents a function, where the graph is a function if any vertical line intersects it at most once.

Independent Variable

A variable whose value does not depend on another variable, representing the input or $x$-variable of a function.

Dependent Variable

A variable whose value depends on another variable, representing the output or $y$-variable of a function.

Parallelogram

A quadrilateral with opposite sides that are parallel and congruent, opposite angles that are congruent, consecutive angles that are supplementary, and diagonals that bisect each other.

Rectangle

A parallelogram with four right angles and congruent diagonals.

Rhombus

A parallelogram with four congruent sides, perpendicular diagonals, and diagonals that bisect opposite angles.

Square

A quadrilateral with four congruent sides, four right angles, congruent diagonals, and perpendicular diagonals.

Linear Function

A function with a degree of one or less that has a constant rate of change and whose graph is a straight line.

Slope

A measure of the steepness of a line, denoted by $m$, calculated as the ratio of vertical change (rise) to horizontal change (run).

Zero of a Linear Function

The value of $x$ that makes the output $f(x)$ equal to $0$, corresponding to the $x$-value of the $x$-intercept on a graph.

Slope-Intercept Form

An equation of a linear function expressed as $f(x) = mx + b$, where $m$ represents the slope and $b$ represents the $y$-intercept.

Parallel Lines

Straight lines in the same plane that are always equidistant and never intersect.

Perpendicular Lines

Two lines that intersect to form right angles measuring $90^\text{o}$.

Coplanar Lines

Lines that lie within the same plane.

Noncoplanar Lines

Lines that cannot be contained within the same plane.

Skew Lines

Noncoplanar lines that do not intersect.

Three Parallel Lines Theorem

A theorem stating that if two coplanar lines are parallel to the same line, then they are parallel to each other.

Parallel Postulate

A postulate stating that given a line and a point not on the line, exactly one line can be drawn through the point parallel to the given line.

Perpendicular Bisector

A line, ray, or segment that intersects a line segment at its midpoint and is perpendicular to it.