upgrade
upgrade
🥑AP Pre-Calculus Unit 3 Vocabulary

144 essential vocabulary terms and definitions for Unit 3 – Trigonometric and Polar Functions

Study Unit 3
Practice Vocabulary
🥑Unit 3 – Trigonometric and Polar Functions
Topics

🥑Unit 3 – Trigonometric and Polar Functions

3.1 Periodic Phenomena

TermDefinition
concavityThe curvature of a function, describing whether the graph curves upward (concave up) or downward (concave down).
cycleA single complete repetition of a periodic pattern that can be used to construct the entire graph of a periodic relationship.
intervals of decreaseSections of a function's domain where the output values are getting smaller as the input increases.
intervals of increaseSections of a function's domain where the output values are getting larger as the input increases.
periodThe smallest positive value k such that a periodic function repeats its pattern, meaning f(x+k) = f(x) for all x in the domain.
periodic functionA function that repeats its values at regular intervals, where f(x+k) = f(x) for all x in the domain, with k being the period.
periodic relationshipA relationship between two variables where output values demonstrate a repeating pattern over successive equal-length intervals as input values increase.
rate of changeThe measure of how quickly a function's output changes relative to changes in its input.
repeating patternA sequence of values or behaviors that recurs at regular intervals in a periodic relationship.

3.10 Trigonometric Equations and Inequalities

TermDefinition
domain restrictionsLimitations on the input values of a function based on mathematical validity, contextual meaning, or extreme values in the data set.
inverse trigonometric functionsFunctions that reverse the operation of trigonometric functions, taking a trigonometric ratio as input and returning an angle measure as output.
periodicA property of trigonometric functions where they repeat their values at regular intervals.
trigonometric equationsEquations that contain trigonometric functions and require finding the values of the variable that satisfy the equation.
trigonometric inequalitiesInequalities that contain trigonometric functions and require finding the values of the variable that satisfy the inequality.

3.11 The Secant, Cosecant, and Cotangent Functions

TermDefinition
cosecant functionThe reciprocal of the sine function, denoted f(θ) = csc θ, defined where sin θ ≠ 0.
cotangent functionThe reciprocal of the tangent function, denoted f(θ) = cot θ, equivalent to cos θ/sin θ where sin θ ≠ 0.
rangeThe set of all possible output values that a function can produce.
reciprocal functionA function formed by taking the reciprocal (1/f) of another function.
secant functionThe reciprocal of the cosine function, denoted f(θ) = sec θ, defined where cos θ ≠ 0.
vertical asymptotesLines where a function approaches infinity; for secant and cosecant functions, these occur where cosine and sine equal zero, respectively.

3.12 Equivalent Representations of Trigonometric Functions

TermDefinition
algebraic manipulationThe process of rewriting expressions using algebraic operations to transform them into equivalent forms.
cosine sum identityThe trigonometric identity cos(α + β) = cos α cos β - sin α sin β, which expresses the cosine of a sum of two angles.
difference identitiesTrigonometric identities derived from sum identities by substituting negative angles, used to express trigonometric functions of angle differences.
domain restrictionsLimitations on the input values of a function based on mathematical validity, contextual meaning, or extreme values in the data set.
double-angle identitiesTrigonometric identities that express trigonometric functions of twice an angle in terms of functions of the original angle.
equivalent analytic representationsDifferent algebraic forms of trigonometric expressions that are mathematically equal and can reveal different properties or simplify problem-solving.
equivalent formsDifferent ways of writing the same mathematical expression that have equal values for all valid inputs.
Pythagorean identityThe fundamental trigonometric identity sin² θ + cos² θ = 1, derived from the Pythagorean Theorem applied to the unit circle.
sine sum identityThe trigonometric identity sin(α + β) = sin α cos β + cos α sin β, which expresses the sine of a sum of two angles.
trigonometric equationsEquations that contain trigonometric functions and require finding the values of the variable that satisfy the equation.
trigonometric expressionsMathematical expressions involving trigonometric functions such as sine, cosine, tangent, and their reciprocals.
trigonometric identityAn equation involving trigonometric functions that is true for all values in the domain of the functions.
trigonometric inequalitiesInequalities that contain trigonometric functions and require finding the values of the variable that satisfy the inequality.
unit circleA circle with radius 1 centered at the origin, used to define trigonometric functions where a point on the circle has coordinates (cos θ, sin θ).

3.13 Trigonometry and Polar Coordinates

TermDefinition
angle in standard positionAn angle positioned in the coordinate plane with its vertex at the origin and one ray coinciding with the positive x-axis.
complex numberA number of the form a + bi, where a and b are real numbers and i is the imaginary unit.
complex planeA coordinate system where complex numbers are represented as points, with the real part on the horizontal axis and the imaginary part on the vertical axis.
originThe central point in a polar coordinate system from which all distances (radii) are measured.
polar coordinateA coordinate system in which points are located by their distance from the origin (radius r) and their angle measure (θ) from the positive x-axis.
polar coordinate systemA coordinate system based on circles centered at the origin and lines through the origin, where points are located using an ordered pair (r, θ).
radiusIn polar coordinates, the distance from the origin to a point, represented by |r|.
rectangular coordinateAn ordered pair (x, y) representing the horizontal and vertical position of a point in the plane.
rectangular coordinate systemA coordinate system where points are located using an ordered pair (x, y) representing horizontal and vertical distances from the origin.
terminal rayThe ray that forms the final side of an angle in standard position.

3.14 Polar Function Graphs

TermDefinition
angle measureThe input value in a polar function that represents the direction from the positive x-axis, typically measured in radians or degrees.
domainThe set of all possible input values for which a function is defined.
originThe central point in a polar coordinate system from which all distances (radii) are measured.
polar coordinateA coordinate system in which points are located by their distance from the origin (radius r) and their angle measure (θ) from the positive x-axis.
polar functionsFunctions of the form r = f(θ) where the input is an angle measure and the output is a radius, used to create graphs in polar coordinates.
positive x-axisThe reference direction in a polar coordinate system from which angle measures are taken.
radiusIn polar coordinates, the distance from the origin to a point, represented by |r|.

3.15 Rates of Change in Polar Functions

TermDefinition
average rate of changeThe change in the output of a function divided by the change in the input over a specified interval, calculated as (f(b) - f(a))/(b - a) for the interval [a, b].
polar functionA function of the form r = f(θ) that describes a curve in the polar coordinate system, where r is the distance from the origin and θ is the angle.
relative extremumA point on a function where the function changes from increasing to decreasing (relative maximum) or from decreasing to increasing (relative minimum).

3.2 Sine, Cosine, and Tangent

TermDefinition
cosine functionA trigonometric function that gives the x-coordinate (horizontal displacement from the y-axis) of a point on the unit circle corresponding to a given angle.
radian measureThe measure of an angle defined as the ratio of the arc length subtended by the angle to the radius of the circle.
sine functionA trigonometric function that gives the y-coordinate (vertical displacement from the x-axis) of a point on the unit circle corresponding to a given angle.
standard positionThe position of an angle with its vertex at the origin and its initial side along the positive x-axis.
tangent functionA trigonometric function, denoted f(θ) = tan θ, that gives the slope of the terminal ray of an angle in standard position on the unit circle.
terminal rayThe ray that forms the final side of an angle in standard position.
unit circleA circle with radius 1 centered at the origin, used to define trigonometric functions where a point on the circle has coordinates (cos θ, sin θ).

3.3 Sine and Cosine Function Values

TermDefinition
angle in standard positionAn angle positioned in the coordinate plane with its vertex at the origin and one ray coinciding with the positive x-axis.
circle centered at the originA circle whose center is at the point (0, 0) on the coordinate plane.
coordinatesThe ordered pair (x, y) that specifies the location of a point on a coordinate plane.
cosine functionA trigonometric function that gives the x-coordinate (horizontal displacement from the y-axis) of a point on the unit circle corresponding to a given angle.
equilateral triangleA triangle with all three sides equal in length and all angles measuring 60°.
isosceles right triangleA right triangle with two equal sides and angles of 45°-45°-90°.
multiples of π/4Angles that are integer multiples of π/4 radians (45°), including π/4, π/2, 3π/4, π, etc.
multiples of π/6Angles that are integer multiples of π/6 radians (30°), including π/6, π/3, π/2, 2π/3, etc.
quadrantOne of the four regions of the coordinate plane divided by the x-axis and y-axis.
radianA unit of angle measure where one radian is the angle formed when the arc length equals the radius of the circle.
radiusIn polar coordinates, the distance from the origin to a point, represented by |r|.
sine functionA trigonometric function that gives the y-coordinate (vertical displacement from the x-axis) of a point on the unit circle corresponding to a given angle.
terminal rayThe ray that forms the final side of an angle in standard position.

3.4 Sine and Cosine Function Graphs

TermDefinition
cosine functionA trigonometric function that gives the x-coordinate (horizontal displacement from the y-axis) of a point on the unit circle corresponding to a given angle.
domainThe set of all possible input values for which a function is defined.
oscillateTo move back and forth between two values in a regular, repeating pattern.
sine functionA trigonometric function that gives the y-coordinate (vertical displacement from the x-axis) of a point on the unit circle corresponding to a given angle.
standard positionThe position of an angle with its vertex at the origin and its initial side along the positive x-axis.
terminal rayThe ray that forms the final side of an angle in standard position.
unit circleA circle with radius 1 centered at the origin, used to define trigonometric functions where a point on the circle has coordinates (cos θ, sin θ).
x-coordinateThe horizontal position of a point, representing its distance from the y-axis.
y-coordinateThe vertical position of a point, representing its distance from the x-axis.

3.5 Sinusoidal Functions

TermDefinition
amplitudeThe absolute value of the coefficient a in a sinusoidal function, representing the maximum distance from the midline to the peak or trough of the graph.
concave downA characteristic of a graph where the rate of change is decreasing, creating a curve that opens downward.
concave upA characteristic of a graph where the rate of change is increasing, creating a curve that opens upward.
cosine functionA trigonometric function that gives the x-coordinate (horizontal displacement from the y-axis) of a point on the unit circle corresponding to a given angle.
even functionA function that is graphically symmetric over the line x = 0 and satisfies the property f(−x) = f(x).
frequencyThe number of complete cycles of a sinusoidal function that occur over a unit interval of input values.
midlineThe horizontal line around which a sinusoidal function oscillates, located at y = d in the function a sin(b(θ + c)) + d.
odd functionA function that is graphically symmetric about the point (0,0) and satisfies the property f(−x) = −f(x).
periodThe smallest positive value k such that a periodic function repeats its pattern, meaning f(x+k) = f(x) for all x in the domain.
reflective symmetryA property of a graph that is mirror-symmetric across a line; the cosine function has reflective symmetry over the y-axis.
rotational symmetryA property of a graph that looks the same when rotated 180 degrees about a point; the sine function has rotational symmetry about the origin.
sine functionA trigonometric function that gives the y-coordinate (vertical displacement from the x-axis) of a point on the unit circle corresponding to a given angle.
sinusoidal functionA function of the form f(θ) = a sin(b(θ + c)) + d or g(θ) = a cos(b(θ + c)) + d, where a, b, c, and d are real numbers and a ≠ 0.

3.6 Sinusoidal Function Transformations

TermDefinition
amplitudeThe absolute value of the coefficient a in a sinusoidal function, representing the maximum distance from the midline to the peak or trough of the graph.
horizontal dilationA transformation that stretches or compresses the graph of a function horizontally by multiplying the input by a constant factor b, written as g(x) = f(bx).
horizontal translationA transformation that shifts the graph of a function left or right by adding a constant to the input, written as g(x) = f(x + h).
midlineThe horizontal line around which a sinusoidal function oscillates, located at y = d in the function a sin(b(θ + c)) + d.
periodThe smallest positive value k such that a periodic function repeats its pattern, meaning f(x+k) = f(x) for all x in the domain.
phase shiftA horizontal translation of a sinusoidal function represented by the constant c, which shifts the graph left or right by -c units.
sinusoidal functionA function of the form f(θ) = a sin(b(θ + c)) + d or g(θ) = a cos(b(θ + c)) + d, where a, b, c, and d are real numbers and a ≠ 0.
vertical dilationA transformation that stretches or compresses the graph of a function vertically by multiplying the function by a constant factor a, written as g(x) = af(x).
vertical shiftA vertical translation of a sinusoidal function represented by the additive constant d, which moves the entire graph up or down and shifts the midline.
vertical translationA transformation that shifts the graph of a function up or down by adding a constant k to the function, written as g(x) = f(x) + k.

3.7 Sinusoidal Function Context and Data Modeling

TermDefinition
amplitudeThe absolute value of the coefficient a in a sinusoidal function, representing the maximum distance from the midline to the peak or trough of the graph.
contextual domainThe range of input values for which a sinusoidal function model is meaningful and applicable within a real-world context.
frequencyThe number of complete cycles of a sinusoidal function that occur over a unit interval of input values.
periodThe smallest positive value k such that a periodic function repeats its pattern, meaning f(x+k) = f(x) for all x in the domain.
periodic phenomenaEvents or patterns that repeat at regular intervals over time or space.
phase shiftA horizontal translation of a sinusoidal function represented by the constant c, which shifts the graph left or right by -c units.
sinusoidal functionA function of the form f(θ) = a sin(b(θ + c)) + d or g(θ) = a cos(b(θ + c)) + d, where a, b, c, and d are real numbers and a ≠ 0.
sinusoidal regressionA statistical method using technology to fit a sinusoidal function to a data set by estimating the best-fit parameters.
vertical shiftA vertical translation of a sinusoidal function represented by the additive constant d, which moves the entire graph up or down and shifts the midline.

3.8 The Tangent Function

TermDefinition
additive transformationA transformation of a function involving addition or subtraction, resulting in vertical and horizontal translations.
asymptoteLines that a graph approaches but never reaches, indicating behavior at infinity or at points of discontinuity.
concave downA characteristic of a graph where the rate of change is decreasing, creating a curve that opens downward.
concave upA characteristic of a graph where the rate of change is increasing, creating a curve that opens upward.
cosine functionA trigonometric function that gives the x-coordinate (horizontal displacement from the y-axis) of a point on the unit circle corresponding to a given angle.
horizontal dilationA transformation that stretches or compresses the graph of a function horizontally by multiplying the input by a constant factor b, written as g(x) = f(bx).
horizontal translationA transformation that shifts the graph of a function left or right by adding a constant to the input, written as g(x) = f(x + h).
multiplicative transformationA transformation of a function involving multiplication, resulting in vertical and horizontal dilations.
periodThe smallest positive value k such that a periodic function repeats its pattern, meaning f(x+k) = f(x) for all x in the domain.
periodicA property of trigonometric functions where they repeat their values at regular intervals.
phase shiftA horizontal translation of a sinusoidal function represented by the constant c, which shifts the graph left or right by -c units.
point of inflectionA point on the graph of a polynomial where the concavity changes from concave up to concave down or vice versa, occurring where the rate of change changes from increasing to decreasing or decreasing to increasing.
reflection over the x-axisA transformation that flips the graph of a function across the x-axis, occurring when the multiplicative factor is negative in a vertical dilation.
reflection over the y-axisA transformation that flips the graph of a function across the y-axis, occurring when the multiplicative factor is negative in a horizontal dilation.
sine functionA trigonometric function that gives the y-coordinate (vertical displacement from the x-axis) of a point on the unit circle corresponding to a given angle.
slopeThe rate of change of a line, representing how much the output changes for each unit change in the input.
standard positionThe position of an angle with its vertex at the origin and its initial side along the positive x-axis.
tangent functionA trigonometric function, denoted f(θ) = tan θ, that gives the slope of the terminal ray of an angle in standard position on the unit circle.
terminal rayThe ray that forms the final side of an angle in standard position.
unit circleA circle with radius 1 centered at the origin, used to define trigonometric functions where a point on the circle has coordinates (cos θ, sin θ).
vertical dilationA transformation that stretches or compresses the graph of a function vertically by multiplying the function by a constant factor a, written as g(x) = af(x).
vertical translationA transformation that shifts the graph of a function up or down by adding a constant k to the function, written as g(x) = f(x) + k.

3.9 Inverse Trigonometric Functions

TermDefinition
arccosineThe inverse function of cosine, denoted cos⁻¹(x), that returns an angle whose cosine equals the input value.
arcsineThe inverse function of sine, denoted sin⁻¹(x), that returns an angle whose sine equals the input value.
arctangentThe inverse function of tangent, denoted tan⁻¹(x), that returns an angle whose tangent equals the input value.
inverse trigonometric functionsFunctions that reverse the operation of trigonometric functions, taking a trigonometric ratio as input and returning an angle measure as output.
invertible functionA function that has an inverse function; a one-to-one function where each output corresponds to exactly one input.
periodicA property of trigonometric functions where they repeat their values at regular intervals.
restricted domainA limited interval of input values for a trigonometric function that makes it one-to-one and therefore invertible.