Homework help please Initial phase angle?

[efairall]

A wave is propagating down a string having a diameter of 0.0013 m and a density of
5240 kg/m3. The wave has the form y = A sin(k x - w t + beta)
where A = 0.011 m, w = 59.8 rad/s, and k = 72.4 rad/m.
the velocity of propagation of the wave is 0.825967 m/s

The transverse speed @ y/@t is 0.177606 m/s at x = 0.0102762 m and t = 0.00385686 s.
What is the initial phase angle beta if we assume that 0 < k x - w t + beta < pi ?
Answer in units of rad.

 

[Redbelly98]

What have you attempted so far towards solving this?

 

[efairall]

i have used the formula.. zy/zt =wAcos((kx - wt + (beta))
and solved for beta. i got an answer 0.78 and it was wrong.

 

[Redbelly98]

Double-check your +/- signs, what's the derivative of -wt?

You're on the right track.