Math Problem Statement

What is the amplitude, period, vertical shift and phase shift

What is the amplitude, period, vertical shift, and phase shift of the function y = cos(x - π/2)?

Solution

Let's break down the function you provided:

y=cos(xπ2)y = \cos\left(x - \frac{\pi}{2}\right)

This is a cosine function with a horizontal (phase) shift. Let's analyze the various characteristics of the graph:

1. Amplitude:

The amplitude of a cosine function of the form y=Acos(Bx+C)+Dy = A\cos(Bx + C) + D is given by A|A|. In your case, there is no coefficient in front of the cosine function, so the amplitude is: Amplitude=1\text{Amplitude} = 1

2. Period:

The period of a cosine function is calculated using the formula: Period=2πB\text{Period} = \frac{2\pi}{|B|} Here, the function is cos(xπ2)\cos(x - \frac{\pi}{2}), and since there is no coefficient multiplying xx (i.e., B=1B = 1), the period remains: Period=2π1=2π\text{Period} = \frac{2\pi}{1} = 2\pi

3. Vertical Shift:

The vertical shift DD is the constant added or subtracted outside the cosine function. Since there is no constant added, the vertical shift is: Vertical Shift=0\text{Vertical Shift} = 0

4. Phase Shift:

The phase shift CC is determined by the expression inside the cosine function, (xπ2)(x - \frac{\pi}{2}). To find the phase shift, use the formula: Phase Shift=CB\text{Phase Shift} = -\frac{C}{B} Here, C=π2C = -\frac{\pi}{2} and B=1B = 1, so the phase shift is: Phase Shift=π2 to the right.\text{Phase Shift} = \frac{\pi}{2} \text{ to the right.}

Summary:

  • Amplitude: 1
  • Period: 2π2\pi
  • Vertical Shift: 0
  • Phase Shift: π2\frac{\pi}{2} units to the right.

Would you like to see the graph or further details on how to plot it?

Here are 5 related questions for further practice:

  1. How does the amplitude affect the graph of a cosine function?
  2. What happens to the period of the function if the equation is cos(2xπ2)\cos(2x - \frac{\pi}{2})?
  3. How would the graph change if there were a vertical shift, say y=cos(xπ2)+2y = \cos(x - \frac{\pi}{2}) + 2?
  4. What is the period of the function y=sin(xπ)y = \sin(x - \pi)?
  5. How can you calculate the phase shift for the function y=cos(3xπ3)y = \cos(3x - \frac{\pi}{3})?

Tip: When identifying shifts in a function, always look for values added/subtracted inside and outside the trigonometric function. These indicate phase and vertical shifts, respectively.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Cosine Function
Amplitude
Period
Phase Shift
Vertical Shift

Formulas

Amplitude: |A|
Period: 2π / |B|
Phase Shift: -C / B
Vertical Shift: D

Theorems

Properties of Cosine Function
Shifts and Transformations in Trigonometric Functions

Suitable Grade Level

Grades 10-12