Graph the following points on the graphing calculator:
[tex]\[
(0, 6), \left(\frac{\pi}{2}, 7\right), (\pi, 8), \left(\frac{3\pi}{2}, 7\right), (2\pi, 6)
\][/tex]

Explain how to use the graph to write an equation to model the curve's height. Be sure to identify the pattern of the points in your explanation and identify the values of [tex]$a$[/tex] and [tex]$k$[/tex].



Answer :

To graph the points [tex]$(0,6)$[/tex], [tex]$\left(\frac{\pi}{2}, 7\right)$[/tex], [tex]$(\pi, 8)$[/tex], [tex]$\left(\frac{3 \pi}{2}, 7\right)$[/tex], and [tex]$(2 \pi, 6)$[/tex] and write an equation to model these points, follow these steps:

### Step-by-Step Solution:

#### Plot the Points:

1. Plotting [tex]$(0,6)$[/tex]: Start by plotting the point [tex]$(0,6)$[/tex] on the graph.
2. Plotting [tex]$\left(\frac{\pi}{2}, 7\right)$[/tex]: Next, find [tex]$\frac{\pi}{2}$[/tex] on the x-axis and plot the point at a height of 7.
3. Plotting [tex]$(\pi, 8)$[/tex]: Similarly, plot the point [tex]$(\pi, 8)$[/tex] where [tex]$\pi$[/tex] is on the x-axis and the height is 8.
4. Plotting [tex]$\left(\frac{3 \pi}{2}, 7\right)$[/tex]: Move to [tex]$\frac{3 \pi}{2}$[/tex] on the x-axis and plot at a height of 7.
5. Plotting [tex]$(2 \pi, 6)$[/tex]: Finally, find [tex]$2\pi$[/tex] on the x-axis and plot the point at height 6.

#### Analyzing the Pattern:

- Notice that the points rise and fall in a symmetrical, periodic manner, suggesting a sinusoidal pattern.
- The points demonstrate an oscillation pattern typical of sine or cosine functions with a period of [tex]$2\pi$[/tex].

#### Determine the Equation:

- The pattern suggests using a sine or cosine function. In this case, we will use the cosine function as it starts at the middle value and goes up, then down, and back up.

- Amplitude (a):
- The maximum value is 8 and the minimum value is 6.
- Thus, the middle value (average) is [tex]$\frac{8+6}{2} = 7$[/tex].
- Amplitude [tex]$a$[/tex] is half the distance between the maximum and minimum value: [tex]\[ a = \frac{8 - 6}{2} = 1 \][/tex]

- Vertical Shift (k):
- The middle or average value that the function oscillates around is 7, so [tex]$k = 7$[/tex].

- Period:
- The period of a cosine function [tex]$f(x) = a\cos(bx) + k$[/tex] is determined by [tex]$2\pi/b$[/tex].
- Since the period is [tex]$2\pi$[/tex],
- we get [tex]$b = 1$[/tex] (because [tex]$2\pi/1 = 2\pi$[/tex]).

##### Equation:

Combining these values, the equation modeling the points is:
[tex]\[ y = 1 \cos(x) + 7 = \cos(x) + 7 \][/tex]

- The equation takes the form:
[tex]\[ y = a \cos(bx) + k \][/tex]

with [tex]\(a = 1\)[/tex] (amplitude), [tex]\( b = 1 \)[/tex] (period coefficient), and [tex]\( k = 7 \)[/tex] (vertical shift).

### Conclusion:

To model the given points graphically, you will have:
[tex]\[ y = \cos(x) + 7 \][/tex]

This equation fits the observations, with the points oscillating between [tex]$8$[/tex] and [tex]$6$[/tex], centered around [tex]$7$[/tex].

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