# Finding the phase shift?

• Jan 16th 2011, 04:22 PM
homeylova223
Finding the phase shift?
Can anyone help me find the phase shift for this equation
y=-4 cos(pi/6)(1)+c)+77
According to the back of my book the phase shift is .5 but I am not sure how to find that can anyone help me?(Bow)
• Jan 16th 2011, 04:32 PM
dwsmith
Quote:

Originally Posted by homeylova223
Can anyone help me find the phase shift for this equation
y=-4 cos(pi/6)(1)+c)+77
According to the back of my book the phase shift is .5 but I am not sure how to find that can anyone help me?(Bow)

I can't remember what a phase shift is, but if you can remind me, I will give it a go.
• Jan 16th 2011, 04:41 PM
pickslides
I think the OP requires the horizontal shift which is 'c' in $\displaystyle \displastyle y=A\cos b(x-c)+d$

Can the OP please re-post the equation as the brackets are not complete.
• Jan 16th 2011, 04:48 PM
homeylova223
They do not give me C they want me to find it. However I cannot find it this is what I have done
y=-4 cos (pi/6(1)-c)+77
-77=-4cos(pi/6-c)
19.5=cos(pi/6-c)
And this is where I am stuck really the problem claim it is a sinusoidal function if that help explain things.
But they gave me the amplitude, the vertical shift, and the period but they did not give me c or the phase shift so I guess they want me to find it inside the function.
• Jan 16th 2011, 04:53 PM
homeylova223
Sorry I mean c=.5 I just dont know how to find c. So I am trying to use the equation to find c.