I am having a problem finding where to start. The problem is this: A loudspeaker at the orgin emits sound waves on a day where the speed of sound is 340 m/s. A crest of the wave simultaneously passes listeners at the (x,y) coordinates (40m,0m) and (0m,30m). What are the lowest two frequencies of the sound? If the question asks for do different frequecies then there must be two different waves, right? I am having trouble thinking how to relate anything to finding the frequecy. Thanks for your help.