I've got to find the period, amplitude and graph a trig function similar to the one below and I'm not sure if I'm on the right track. I haven't posted the exact question so if something doesn't look right with the function that's why.

$\displaystyle f(d) = 8 - 3\cos(2\pi d) $

From that I think it's:

Amplitude: 3

Period: 1 ie $\displaystyle \frac{2\pi}{2\pi}$

Is raised up 8 on the y/sin axis so the max and minimum values are 11 and 5 with nothing to shift it right so graphing will pass through the point (0, 11)

Does that all seem right?

And what changes by there being a minus sign between the 8 and 3 rather than an addition?

Would the y axis start at the minimum point (5) rather than the maximum (11)?

Thanks