Calculating Frequency Difference of a Rotating Siren - How Fast Must It Spin?

[sirclash]

Homework Statement

A siren has two loud speakers attached to a rotating disk. The disks radius is 3m. The speakers emit a sound frequency of 300 Hz.(Speed of sound in air is 344 m/s)
A)How fast does the disk need to spin for an observer standing some distance away to perceive two frequencies that are different by by 50 Hz.
B)Whats the difference of the two frequencies if the disk is tilted by 50 degrees?(Hint: velocity is a vector)

Homework Equations

The Attempt at a Solution

Please help me get started. I'm assuming its both stationary observer and source but i don't know how to implement a rotation siren. Does that mean the source is actually moving?

 

[ideasrule]

Yes, the siren is actually moving. What's the tangential velocity of a rotating disk?

 

[sirclash]

Well that's Vt=w*r, but i don't see how you obtain that from given just frequency and radius. Is their a formula that that will help get me started.
Heres some formulas including w.
k=w/v
w=2*pi/T
But none of these help, yet atleast