Question

if the reflected and the incident sound waves are at an angle of 120 degree with each other the incident angle should be of what measurement

Answer 1

60° is right answer

Answer 2

According to the laws of reflection, the angle of incidence is equal to the angle of reflection.
Hence, the angle of incidence + angle of reflection = 2 times the angle of incidence
So, 120 degrees = 2 times of the angle of incidence
Therefore, the angle of incidence is equal to 120 / 2 = 60 degrees