# Thread: Graphing some Sin/Cos waves =/

1. ## Graphing some Sin/Cos waves =/

Here's the problem(s)

For #3 I need to find the cos graph equation here's what I got: shift to the right 2, Amplitude = 3, b = π/2 (pi/2)

equation: y=3cosπ/2(x-2)

I'm just not sure if i have it in the right format or if I'm even right

Attempt for #4 Amplitude=2 Shift left = 1 Shift up= 3

I'm just not sure if I am doing it right for both of them

2. Originally Posted by SarahGilf
Here's the problem(s)

For #3 I need to find the cos graph equation here's what I got: shift to the right 2, Amplitude = 3, b = π/2 (pi/2)

equation: y=3cosπ/2(x-2)

I'm just not sure if i have it in the right format or if I'm even right

Attempt for #4 Amplitude=2 Shift left = 1 Shift up= 3

I'm just not sure if I am doing it right for both of them
For #3, you don't need to shift the graph, just make your amplitude of 3 a -3 and that flips the graph upside down. You find the period using $\frac{2\pi}{B} = 4$ So, the period change will be $\frac{\pi}{2}$
So your equation for #3 is: $y= -3 cos(\frac{\pi}{2}x)$

3. Originally Posted by mollymcf2009
For #3, you don't need to shift the graph, just make your amplitude of 3 a -3 and that flips the graph upside down. You find the period using $\frac{2\pi}{B} = 4$ So, the period change will be $\frac{\pi}{2}$
So your equation for #3 is: $y= -3 cos(\frac{\pi}{2}x)$

Ah ok thanks a bunch

any idea on problem 4?

4. Originally Posted by SarahGilf
Here's the problem(s)

For #3 I need to find the cos graph equation here's what I got: shift to the right 2, Amplitude = 3, b = π/2 (pi/2)

equation: y=3cosπ/2(x-2)

I'm just not sure if i have it in the right format or if I'm even right

Attempt for #4 Amplitude=2 Shift left = 1 Shift up= 3

I'm just not sure if I am doing it right for both of them
#4 look right to me! ***Actually I take that back, I had to look at it again. Looks like your period is wrong. To find the period on this one, distribute your terms after you sin function:

$0 < \frac{\pi}{4}x + \frac{\pi}{4} < 2\pi$

Your period/end points of the new period should be -1, 7

**Remember that for the sin graph, your periods will not begin at the top and bottom of the curve, those will be for your cos graph. This is kind of silly, but I try to remember that a complete period of the cos graph has one big bump and a complete period of the sin graph has 2 bumps. LOL! Hope that helps!