McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
7. Graphing Trigonometric Functions
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Exercise 1 Page 841

In the sine function y=asin bθ , the amplitude is |a| and the period is 360^(∘)|b|.

Amplitude: 4
Period: 360^(∘)
Graph:

Practice makes perfect

We will find the period and amplitude of the given sine function. Then, we will graph the function. Let's do these things one at a time.

Finding Period and Amplitude

Let's consider the general form of a sine function. y= a sin bθ Here | a| is the amplitude, | b| is the number of cycles in the interval from 0^(∘) to 360^(∘) , and 360^(∘)| b| is the period of the function. Let's now consider the given function. y=4sin θ ⇔ y= 4 sin 1θ In this equation we have that a= 4 and b= 1. Since |4|=4, the amplitude of the graph of the function is 4. This means that the maximum is 4 and the minimum is - 4. Amplitude:& 4 Maximum:& 4 Minimum:& - 4 With b= 1, we know that there is 1 cycle from 0^(∘) to 360^(∘). The period of the graph of a sine function is 360^(∘)| b|. Since we already know that b= 1, we can find the period of the given function.
Period=360^(∘)/|b|
Period=360^(∘)/| 1|
Period=360^(∘)/1
Period=360^(∘)
The period of the graph of our function is 360^(∘).

Sketching the Graph

To graph the given function, we should first identify the points where the θ-intercepts occur. These points can be identified for a sine function as shown in the table below. By substituting b=1, we can evaluate these points.

θ-intercepts b=1 Simplify
(0,0) (0,0) ( 0,0)
( 1/2 * 360^(∘)/b,0 ) ( 1/2 * 360^(∘)/1,0 ) ( 180^(∘),0)
(360^(∘)/b,0) (360^(∘)/1,0) ( 360^(∘) ,0)

We can graph one cycle of the function by substituting calculated points and connecting them with a smooth curve. Remember that the maximum value is 4 and the minimum value is - 4. Let's do it!

Now, we can extend the graph by repeating the cycle to the left and right.