Help with Oscillations

[mattmannmf]

the position of the center of the box shown is given by the equation

x = 5.3 m * cos(20/sec * t)
(a) What is the position of the box 2 seconds after the oscillations have started?

(b) What is the amplitude of the box's oscillations?

(c) What is the period of the box's oscillations?

(d) What is the box's maximum velocity?

(e) What is the box's maximum acceleration?

(f) How long does it take the box to move from -2.65 m to +2.65 m?

for a, i just plugged in 2 for t and got 4.98...but that's wrong not sure where to go from there
Calc:
5.3*cos(20/(1/cos(2)))...sec= 1/cos

 

[Astronuc]

Start with x = A cos (ωt). What is A? What is ω?

A = 5.3 m, and ω = 20 s^-1

 

[mattmannmf]

so x=5.3*cos(20E-1*2)...5.28?