Understanding Sound Interference

[team31]

I'm having trouble with the interference of sound. As the given function of the combined Amplidude A=2Acos(PI*d*sin(θ)/λ), hence the interfernce max will be d*sin(θ)=n*λ, and min will be d*sin(θ)=(n+1/2)*λ. I chose my sound frequency and wavelength. so I figule out the nth max and nth min, but when i tried to plot the graph of the combined Amplidude function, it's amplitude value is not going up and down as the angle increase(which I throught it would becasue the max and min) but just simply decrease from 0 to about 90 degree then it increase back up. so How do we know if it's a max or min, since it's all decreasing in a steady rate?

 

[OlderDan]

I am not recognizing what you are doing here. What is the arrangement of the sound sources that are interfering?

 

[team31]

Nevermind, I was finally figure out that cos is in radians and sin was in degree. Now my graph matches with my predictions. Thanks anyway