# Finding the Phase Shift of a Function.

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• Nov 9th 2009, 05:25 PM
rgrimm01
Finding the Phase Shift of a Function.
I have the function (1/37)cos3t+(6/37)sin3t. I am asked to find the amplitude, which I found quite easily, and the phase shift, which I am having trouble finding. Any help, even a little nudge in the general direction of the answer, would help. Thanks in advance.
• Nov 9th 2009, 10:48 PM
CaptainBlack
Quote:

Originally Posted by rgrimm01
I have the function (1/37)cos3t+(6/37)sin3t. I am asked to find the amplitude, which I found quite easily, and the phase shift, which I am having trouble finding. Any help, even a little nudge in the general direction of the answer, would help. Thanks in advance.

You rewrite this in the form:

$\displaystyle A \sin(\omega t+\phi)$

using trig (the $\displaystyle \sin$ may be a $\displaystyle \cos$ if you are measuring phase shift wrt $\displaystyle \cos$ rather than $\displaystyle \sin$)

Then $\displaystyle A$ is the amplitude and $\displaystyle \phi$ is the phase.

CB