Periodic Phenomena and Trigonometry

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Questions and Answers

What distinguishes a periodic function from other types of functions?

  • It has a parabolic shape.
  • It has a linear relationship between input and output values.
  • It grows exponentially over time.
  • It repeats its pattern over regular intervals. (correct)

The period of a periodic function is the shortest interval over which the function's pattern repeats.

True (A)

If a function $f(x)$ has a period of $k$, algebraically, how is this periodicity expressed?

f(x + k) = f(x)

In a clock that is functioning improperly and moving twice as fast, the time between the minute hand pointing directly up at the 12 is an example of a shortened ______.

<p>period</p> Signup and view all the answers

If angle $\theta$ is in standard position, what defines its reference angle?

<p>The acute angle formed by the terminal side of $\theta$ and the x-axis. (A)</p> Signup and view all the answers

An angle in standard position and its coterminal angle always share the same terminal side.

<p>True (A)</p> Signup and view all the answers

Convert 1 degree into radians.

<p>$\frac{\pi}{180}$</p> Signup and view all the answers

The measure of an angle in standard position is the ratio of the length of the arc of a circle centered at the origin created by the angle to the ______ of that same circle.

<p>radius</p> Signup and view all the answers

Which of the following statements about sine and cosine is correct?

<p>Sine is the ratio of the vertical displacement from the x-axis to the distance to the origin. (C)</p> Signup and view all the answers

On the unit circle, the cosine of an angle corresponds to the y-coordinate of the point where the terminal side of the angle intersects the circle.

<p>False (B)</p> Signup and view all the answers

Given a point $(x, y)$ on the unit circle, what is the formula for $\tan(\theta)$?

<p>$\frac{y}{x}$</p> Signup and view all the answers

The sine function gives the ______ displacement from the x-axis.

<p>vertical</p> Signup and view all the answers

Match each trigonometric function with its reciprocal function:

<p>Sine = Cosecant Cosine = Secant Tangent = Cotangent</p> Signup and view all the answers

Which describes the graph of the function $f(x) = \sin(x)$?

<p>Odd Function (B)</p> Signup and view all the answers

The graph of $f(x) = \cos(x)$ has rotational symmetry about the origin.

<p>False (B)</p> Signup and view all the answers

What is the term for half the difference between the maximum and minimum values of a sinusoidal function?

<p>amplitude</p> Signup and view all the answers

In a sinusoidal function, the ______ is the average of the maximum and minimum values.

<p>midline</p> Signup and view all the answers

What does 'd' represent in the sinusoidal function $f(\theta) = \sin(\theta) + d$?

<p>Vertical Translation (A)</p> Signup and view all the answers

In the sinusoidal function $f(θ) = a \sin θ$, the constant a affects the period of the function.

<p>False (B)</p> Signup and view all the answers

How are the period and frequency of a sinusoidal function related?

<p>They are reciprocals of each other.</p> Signup and view all the answers

A horizontal translation is otherwise known as a ______ shift.

<p>phase</p> Signup and view all the answers

Match $y = 2\sin(\frac{1}{2}x)$ to a description.

<p>amplitude: 2, period: 4$\pi$ (B)</p> Signup and view all the answers

The transformations of functions $y = \cos(2x + \pi)$ consists of a horizontal dilation of SF = 2, and the phase shift to the right $PS = \frac{\pi}{2}$

<p>False (B)</p> Signup and view all the answers

Which parameters of the sinusoidal function have to be calculated to determine $A\sin[B(x – C)] + D$?

<p>Amplitude, Vertical Translation, Horizontal Stretch, Phase Shift</p> Signup and view all the answers

To model periodic data, ______ regression is used.

<p>sinusoidal</p> Signup and view all the answers

Which of the following defines the location of a point P on a unit circle that corresponds to an angle $\theta$ in standard position:

<p>(cos$\theta$, sin$\theta$) (A)</p> Signup and view all the answers

Coterminal angles must have the same cosine and sine values.

<p>True (A)</p> Signup and view all the answers

What does a negative angle in standard position indicate about the direction of rotation?

<p>Clockwise rotation</p> Signup and view all the answers

If $\tan(\theta) = 1$ and $0 \le \theta \le 2\pi$, then $\theta$ could be ______.

<p>$\frac{\pi}{4}$ or $\frac{5\pi}{4}$</p> Signup and view all the answers

Which change occurs to a sinusoidal function if its period increases?

<p>It stretches horizontally. (A)</p> Signup and view all the answers

Increasing the amplitude of a sine function results in a graph that oscillates between higher and lower y-values, but the period remains unchanged.

<p>True (A)</p> Signup and view all the answers

State the period and amplitude of the sine wave (y = 5 \sin(3x)).

<p>Period: (\frac{2\pi}{3}), amplitude: 5</p> Signup and view all the answers

The general form of a sinusoidal function allows for horizontal shifts, which are also known as ______ shifts.

<p>phase</p> Signup and view all the answers

Where does the graph of y=cos x, -2$\pi$$\le$ x$\le$0 start?

<p>(-2$\pi$,1) (A)</p> Signup and view all the answers

The midline of a sinusoidal function represents the average value between its maximum and minimum points.

<p>True (A)</p> Signup and view all the answers

Describe the roles of parameters A and B in transforming $y = A\sin(Bx)$.

<p>A controls the amplitude, B controls the period</p> Signup and view all the answers

In the graphs of trigonometric functions, points of ______ indicate where a function's concavity changes.

<p>inflection</p> Signup and view all the answers

Which of the following describes a vertical dilation?

<p>Stretching the graph vertically away from the x-axis. (D)</p> Signup and view all the answers

When modeling the distance of a point on a rotating Ferris wheel from the ground, a periodic function is appropriate because the motion repeats.

<p>True (A)</p> Signup and view all the answers

If (f(x) = A\sin(Bx + C) + D) models a sinusoidal wave, what parameter directly adjusts the Midline of the wave?

<p>D</p> Signup and view all the answers

The period of the function represented by the equation f(t) = A sin(Bt) is ______.

<p>$\frac{2\pi}{B}$</p> Signup and view all the answers

Flashcards

Periodic Relationship

A relationship where output values repeat over equal input intervals.

Period

The horizontal length of one complete cycle of a periodic function.

Angle

Two rays sharing a common vertex.

Initial Side

Ray on the positive x-axis.

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Terminal Side

Ray that rotates around.

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Positive Angle

Angle rotating counter-clockwise.

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Negative Angle

Angle rotating clockwise.

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Standard Position (Angle)

Angle with vertex at origin, initial side on positive x-axis.

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Quadrantal Angle

Angle in standard position w/ terminal side on an axis.

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Radian Measure

Ratio of arc length to radius.

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Coterminal Angles

Angles sharing the same initial and terminal sides.

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Reference Angle

Positive acute angle formed by terminal side and x-axis.

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Sine (sin)

Ratio of opposite to hypotenuse.

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Cosine (cos)

Ratio of adjacent to hypotenuse.

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Tangent (tan)

Ratio of opposite to adjacent.

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Sine Function (on unit circle)

Vertical displacement from x-axis.

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Cosine Function (on unit circle)

Horizontal displacement from y-axis.

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Period (sinusoidal)

Smallest positive k where f(θ+k) = f(θ).

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Frequency

Number of cycles in an interval.

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Amplitude

Half the difference between maximum & minimum values.

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Midline

Average of max/min values.

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Vertical Translation

Vertical shift of the graph.

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Vertical Dilation

Change in the vertical dimension.

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Horizontal Dilation

Change in the horizontal dimension.

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Phase Shift

Horizontal shift of the graph.

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Study Notes

  • Periodic phenomena are relationships between two variables resulting in output values taking on and repeating a pattern over equal input intervals.
  • The graph of a periodic relationship is determined by a single cycle.
  • The period is the length of the input interval for one cycle.
  • Algebraically, a periodic function is written as f(x + k) = f(x) for all k, where k is the function's period.

Sine, Cosine, and Tangent

  • An angle has two rays with a common vertex.
  • The initial side is a ray on the positive x-axis.
  • The terminal side is a ray that rotates around the origin.

Positive and Negative Angles

  • A positive angle is a rotating counter- clockwise
  • A negative angle is rotating clockwise

Standard Position of an Angle

  • An angle whose vertex is at the origin.
  • An angle whose initial side is the positive x-axis.

Quadrantal Angle

  • An angle is a standard position whose terminal side lies on an axis.
  • The radian measure of an angle in standard position is the ratio of the length of the arc of a circle centered at the origin created by the angle to the radius of that same circle.
  • One revolution is 2π radians, equivalent to 360°.
  • 1 degree = π/180 radians.
  • 1 radian = 180/π ≈ 57 degrees.

Arc Length

  • Arc Length indicated is s, and Radius indicated is r
  • Θ = central angle
  • r = radius
  • s = arc length
  • Formula for arc length: Θ= s/r

Converting between Degrees and Radians:

  • To convert from degrees to radians, multiply by π/180.
  • To convert from radians to degrees, multiply by 180/π.
  • Coterminal angles have the same initial and terminal sides but have different measures.
  • Two methods exist
  • Degrees: Θ ± 360°k, where k equals any integer
  • Radians: Θ ± 2πk, where k equals any integer

Reference Angle

  • A reference angle, in standard position, is the positive, acute angle formed by the terminal side of [Θ] and the x-axis

Reference Angle by Quadrant:

  • Quadrant II: [Θ’ = π - Θ]
  • Quadrant I: [Θ’ = Θ]
  • Quadrant III: [Θ’ = Θ - π]
  • Quadrant IV: [Θ’ = 2π - Θ]

SOH CAH TOA

  • Sine [Θ]= opposite / hypotenuse = y/r
  • Cosine [Θ]= adjacent / hypotenuse = x/r
  • Tangent [Θ]= opposite / adjacent = y/x
  • Also known as tan [Θ]= sin [Θ]/ cos [Θ]

Quadrantal Angles

  • An angle In standard position equals terminal side coincident with the x or y axis

Cosine of Angle

  • Ratio of the horizontal displacement P from y-axis Unit circle cosine equals x coordinate of point P

Tangent of Angle

  • Exists given a slope of the terminal ray
  • Tangent equals the ratio of the vertical displacement over horizontal displacement

Unit Circle

  • [Sin Θ = y], [Csc Θ= 1/y]
  • [Cos Θ = x], [Sec Θ= 1/x]
  • [Tan Θ = y/x], [Cot Θ= x/y]
  • Range of Sine: [-1,1]
  • Range of Cosine: [-1,1]

Unit Circle special cases

  • Sine and Cosine of angles are multiples of π/4.

  • An angle in standard position in a unit circle with a radian measure of π/4 is an angle in an isosceles right triangle.

  • In a unit circle, the coordinates of Point P for an angle in standard position with a measure of π/4 in Quadrant 1, the coordinates are (√2/2, √2/2).

  • Sine and Cosine of angles that are multiples of π/3

  • An angle in standard position in a unit circle with a radian measure of π/3 is an angle in an equilateral triangle.

  • In a unit circle, the coordinates of Point P for an angle in standard position with a measure of π/3 in Quadrant 1, the coordinates are (1/2,√3/2).

  • The sine function of an angle in standard position on the unit circle gives vertical displacement from the x-axis.

  • The cosine function of an angle in standard position on the unit circle gives horizontal displacement from the y-axis.

  • Cosine is just a translation of Sine

Sinusoidal Characteristics

  • The period of a sinusoidal function means the smallest positive value k such that f(Θ+k) = f(Θ) for all (Θ) in the domain.
  • The frequency means the horizontal dilation or # of times the pattern repeats
  • The amplitude is 1/2 the difference between the max and min. value in 1 period
  • The midline is the average of the maximum value and the minimum value.

Transforming sinusoidal

  • [f(x)=Asin[B(x−C)]+D]
  • Where. Reflection happens on x-axis, vertical shift, vertical dilation and horizontal shift are present
  • Vertical Translation: f(Θ) = sinΘ + d or f(Θ) = cosΘ + d, a vertical shift of the graph of sine or cosine, including the midline, by d units.
  • Vertical Dilation: f(Θ) = a sinΘ or f(Θ) = a cosΘ. A vertical dilation of the graph of sine or cosine, where amplitude changes by a factor of |a|. also changed by a factor of.a..
  • Horizontal Dilation: [f(Θ)=sin⁡(bΘ)] or [f(Θ)=cos⁡(bΘ)]. horizontal dilation of the graph of sine or cosine, where period also changes by a factor of
  • Additive Transformation (Horizontal Shift): [f(Θ)=sin⁡(Θ+c)] or [f(Θ)=cos⁡(Θ+c)]. A horizontal translation, also known as the phase shift shift is present of the graph of sine or cosine by c units

Steps for fitting data to the Sinusoidal Function:

$$f(x) = A \sin[B(x – C] + D$$

  • Determine A or Amplitude. A = Largest Data Value – Smallest Data Value/2
  • Determine D or Vertical Translation. Vertical Translation equals a midline D = Largest Data Value + Smallest Data Value / 2
  • Determine B (Horizontal Stretch) by first finding P the Period or the time if takes for data to repeat. So: P = [2π/B], [B =2π/P]

Determine C or the Phase Shift (Horizontal Shift), by using the ordered pair (x, (f(x)) from data where f(x) equals the smallest, answers depend on ordered pair selected so consistency is maintained [f(x)=Asin[B(x−C)] + D], Make sure you factor

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