I am having difficulty grasping what to do for this problem: Two point sources located (0, +/- 2.5(lambda)) are generating waves in phase. Compute the distance from the x-axis to the first nodal line at x=50(lambda) I'm not sure what equations to use. My physics instructor is terrible and we don't even use a text book......instead we have to read his "readings". I don't really grasp wave motion very well..............if u have a link to a wesite that can help be out that would be great. Thanks!