Help with alg 2 prob! plz! its a short, simple graphing one?

Question

I knew how to do this.. but i forget can some kind fellow or fella plz show me

give the period and amplitude of each function.

y= 4 cos (1/2) x

thanks !!!!!

Answer 1

period is 180deg and the amplitude is 4

Answer 2

Simple harmonic motion form is x = A cos (wt + phi)

w = 2pi*f

f = w/2pi

and t = 1/f

A = 4

solving for t, assuming w is 1/2

.5/2pi = 0.7854 = f

1/f = 1/0.7854 = 1.27 sec

Answer 3

I'm only in Algebra 1, and it sucks. But you should buy a graphic calc. :D