Math SAT Terminology + Geometry Vocab/Concepts

Constant

A number with a fixed value; 7 is the constant in 3x + 7.

Variable

A letter or symbol representing a number; x in 3x + 7.

Coefficient

The number multiplying a variable; 3 in 3x.

Term

A number, variable, or product; 3x and 7 are separate terms.

Expression

Numbers and/or variables combined by operations, without an equals sign.

Equation

A statement that two expressions are equal; x + 4 = 9.

Inequality

A comparison using

Evaluate

Substitute given values and calculate; 2x = 6 when x = 3.

Solve

Find the value(s) that make an equation or inequality true.

Simplify

Rewrite an expression in an equivalent, simpler form; 2x + 3x = 5x.

Like Terms

Terms with identical variable parts and exponents; 2x and 5x.

Distributive Property

Multiply each term inside parentheses: a(b + c) = ab + ac.

Order of Operations

Parentheses, exponents, multiply/divide left to right, then add/subtract left to right.

Sum

The result of addition; 4 + 5 has a sum of 9.

Difference

The result of subtraction; 9 − 4 has a difference of 5.

Product

The result of multiplication; 3 × 4 has a product of 12.

Quotient

The result of division; 12 ÷ 3 has a quotient of 4.

Factor

A number that divides another whole number evenly; 4 is a factor of 20.

Multiple

The result of multiplying a number by an integer; 20 is a multiple of 4.

Integer

A whole number, its negative, or zero; examples: −3, 0, 7.

Absolute Value

Distance from zero on a number line; |−5| = 5.

Exponent

Shows how many times a base is multiplied by itself; 3 in 2³.

Square Root

A number whose square equals a given number; √49 = 7 (principal root).

Ratio

A comparison of two quantities by division; 2:3.

Proportion

An equation saying two ratios are equal; 2/3 = 4/6.

Percent

A quantity per hundred; 25% = 25/100 = 0.25.

Mean

Average: add all values and divide by how many there are.

Median

Middle value when data are ordered; average the middle two if needed.

Mode

The value that appears most often in a data set.

Range (Statistics)

Largest data value minus smallest data value.

Slope

Steepness of a line: rise ÷ run, or change in y ÷ change in x.

Unit Rate

A rate for one unit; $6 for 3 apples is $2 per apple.

Point

An exact location with no size; usually named by a capital letter.

Line

A straight path extending forever in both directions.

Line Segment

Part of a line with two endpoints.

Ray

Part of a line with one endpoint, extending forever in one direction.

Endpoint

A point marking the end of a segment or start of a ray.

Plane

A flat surface that extends forever in all directions.

Parallel Lines

Coplanar lines that never intersect.

Perpendicular Lines

Lines that intersect to form 90° angles.

Intersecting Lines

Lines that cross or share at least one point.

Angle

A figure formed by two rays sharing an endpoint.

Vertex

The shared endpoint where two rays form an angle.

Acute Angle

An angle measuring more than 0° and less than 90°.

Right Angle

An angle measuring exactly 90°.

Obtuse Angle

An angle measuring more than 90° and less than 180°.

Straight Angle

An angle measuring exactly 180°.

Complementary Angles

Two angles whose measures add to 90°.

Supplementary Angles

Two angles whose measures add to 180°.

Vertical Angles

Opposite angles formed by intersecting lines; they are congruent.

Adjacent Angles

Angles that share a vertex and side without overlapping interiors.

Angle Bisector

A ray or line dividing an angle into two equal angles.

Transversal

A line that intersects two or more coplanar lines at different points.

Corresponding Angles

Angles in matching positions at two transversal intersections; equal if lines are parallel.

Alternate Interior Angles

Interior angles on opposite sides of a transversal; equal if lines are parallel.

Polygon

A closed, flat figure formed by straight line segments.

Regular Polygon

A polygon with all sides equal and all interior angles equal.

Triangle

A polygon with three sides and three interior angles.

Equilateral Triangle

A triangle with three equal sides and three 60° angles.

Isosceles Triangle

A triangle with at least two equal sides.

Scalene Triangle

A triangle with no equal sides.

Right Triangle

A triangle containing one 90° angle.

Hypotenuse

The longest side of a right triangle, opposite its 90° angle.

Triangle Angle Sum

The three interior angles of any triangle total 180°.

Pythagorean Theorem

In a right triangle, a² + b² = c²; c is the hypotenuse.

Congruent Figures

Figures with the same shape and size.

Similar Figures

Figures with equal corresponding angles and proportional sides.

Quadrilateral

A polygon with four sides.

Parallelogram

A quadrilateral with both pairs of opposite sides parallel.

Rectangle

A quadrilateral with four right angles.

Rhombus

A quadrilateral with four equal sides.

Square

A quadrilateral with four equal sides and four right angles.

Trapezoid (U.S. School Definition)

A quadrilateral with exactly one pair of parallel sides.

Diagonal

A segment connecting two nonadjacent vertices of a polygon.

Perimeter

Total distance around a 2D shape; add its side lengths.

Area

Amount of space inside a 2D figure, measured in square units.

Circle

All points in a plane the same distance from a fixed center.

Radius

Segment from a circle's center to its edge; half the diameter.

Diameter

Segment through a circle's center joining two points on the circle; 2r.

Circumference

Distance around a circle; C = 2πr = πd.

Pi (π)

Ratio of a circle's circumference to diameter; approximately 3.14.

Area of a Rectangle

A = length × width.

Area of a Triangle

A = ½ × base × perpendicular height.

Area of a Circle

A = πr², where r is the radius.

Volume

Space inside a 3D solid, measured in cubic units.

Surface Area

Total area of all outer surfaces of a 3D solid.

Coordinate Plane

A flat grid with perpendicular x- and y-axes.

Origin

The point (0, 0) where the coordinate axes intersect.

Ordered Pair

Two coordinates written (x, y); horizontal position first.

Translation

A slide that moves each point the same distance and direction.

Reflection

A flip across a line, producing a mirror image.

Rotation

A turn of a figure around a fixed point.

Dilation

A resizing that keeps the shape but changes its size by a scale factor.