There is a diagram in my book for this problem... I'll try my best to describe it! There are two speakers (A & B) that form a right triangle (at B) with the listener (C). Suppose that the separation between speakers A and B is 5.00 m and the speakers are vibrating in phase. They are playing identical 125-Hz tones, and the speed of sound is 343 m/s. What is the LARGEST possible distance between speaker B and the observer at C, such that he observes destructive interference. I know how to solve for the smallest possible distance... but I have no idea how to solve for the largest! I thought that the distance could keep increasing...to infinity. I solved for the wavelength using velocity and frequency, which is 343/125 = 2.74 m. I know that a difference in path lengths that is a 1/2 integer number of wavelengths is destructive interference. I would appreciate any help! Thanks!