Answer to Question #60763 in Algebra for callum nord

Question

Right now dealing with transformations of sine and cosine functions. Here's the equation I'm stumped on:
F (x)=3 cos (4 pi x - (pi/2)) - 2

I'm trying to put this into the form:
A cos [B (x - C)] + D
But I can't figure out how to factor the
(4 pi x - (pi/2)) into the form [B(x - C)].
I'm confused because if B is 4pi, and the period is (2pi/B), wouldn't I end up with a pi-less period? I haven't encountered that yet.
Also, if the phase shift is C/B, wouldn't I also end up with a pi-less phase shift?