Air-Track Cart Oscillating on a Spring, solve for time

[Becca93]

Homework Statement
The position of a an air-track cart that is oscillating on a spring is given by (14.0cm)cos[(12.0s-1)t]. At what value t after t=0 is the cart first located at x=2.0 cm?


The attempt at a solution

y = Acos(wt+∅)

y = 14cos(12t)
2 = 14cos(12t)
(1/7) = cos(12t)
12t = cos^-1(1/7)
t = cos^/1(1/7) / 12
t = 6.816 seconds,
incorrect.

Does anyone have any advice on how to proceed with this question?

 

[Doc Al]

When finding the angle, be sure to express it in radians. cos^-1(1/7) = ??

 

[Becca93]

When finding the angle, be sure to express it in radians. cos^-1(1/7) = ??

Thank you!