Representation of the wave crests

[mexqwerty]

I've been trying to do the following question but I can't get the right answer. Also, I put in the wrong thread title but I don't know how to change it (sorry).

An ambulance is at rest in a traffic jam in front of an intersection. At that moment, Jim is driving his car at 88.0 km/h through the intersection as shown in the diagram below. In the diagram, the angle θ = 59.0 °.

What is the doppler shift (Δf = f′–f) heard in the siren sound by Jim, when Jim and the ambulance are positioned as shown on the diagram above? The answer is 0.229 kHZ.

 

[mexqwerty]

Never mind. I got the answer. I was just calculating the wrong vector component. Thanks for looking, anyway.