Answer:
Part a)

Part b)

Explanation:
As we know that the observer is standing in front of one speaker
So here the path difference of the two sound waves reaching to the observer is given as


now phase difference is related with path difference as


here in order to find the wavelength


now we have

Part b)
Now we know that when phase difference is odd multiple of 
then in that case the the sound must be minimum
So nearest value for minimum intensity would be

so we have

so we have

now we have


Answer:
It would appear as a flattened disk with a central bulge and spiral arms, spanning a few degrees across the sky.
Explanation:
I hope this helps! Have a great day!
Anygays-
Well you have to think of it like electricity go through your answer closes to that and figure it out