Calculating Velocity in Simple Harmonic Motion

[TerikE]

Homework Statement

The position of a 49 g oscillating mass is given by x(t)= (2.3cm) cos 11t , where t is in seconds.
Determine the velocity at t = 0.43s

Where:
f= 1.75
t=0.43s
vmax=0.25 m/s

Homework Equations

I'm using v(t)= -vmax sin (2pi*f*t)

The Attempt at a Solution

Using above equation and variables I get 0.0206, which is wrong (mastering physics).

Can't figure this one out..

 

[TerikE]

Annnnd.. I was in deg and not rad.. Funny how something so small can cause such great frustration. Answer is .25