Given the oscillation g() = 5 cos(3t - pi/4), state
i)the amplitude
ii) the period
iii) the horizontal shift in radians
i havent a clue where to start as i have never been taught this before
any help would be great cheers!
$\displaystyle y = Acos(\omega t - \phi )$
A is the amplitude
$\displaystyle \omega$ is the angular frequency, from which we obtain $\displaystyle T = \frac{2 \pi}{\omega}$.
$\displaystyle \phi $ is called the "phase shift."
Are you sure you are looking for the "horizontal shift" in radians? It should be in seconds:
$\displaystyle \omega t - \phi = \omega \left ( t - \frac{\phi}{\omega} \right )$
The term $\displaystyle \frac{\phi}{\omega}$ tells how far we translate the cosine graph to the left (or right if the term is negative), and is what I think your instructor is looking for, not the phase shift.
-Dan