Ok I'm guessing this is simple harmonic motion?

I don't understand how these values relate to the displacement at all, can anyone help?

The displacement,d, in cm, of a particle is given by

d= 3 sin(40 πt) – 4 cos( 40 πt)t≥ 0

· Find expressions for the velocity and acceleration of the particle

· Calculate the velocity and acceleration whent= 2

· Determine when the particle is first at rest

· Calculate the displacement and acceleration when the particle is at rest

(π = pi)

Thanks!