mass-spring system

This question tests your ability to solve second order linear inhomogenous differential equations.
A mass-spring system subject to an external periodic forcing of angular frequency satisfies the differential equation
This equation has a solution in the form .

Find the function .

y(p) is a function of t, the derivatives are just 0, so 12* = cos(Ht)
and i reaaranged to get R(H) but this is wrong.

We define to be the value of for which the function reaches its maximum.
Find .

tried 1/12, as the max value of cos is 1, but this was also wrong...

find .