The question is: "Two travelling waves are superposed on the same string. Waves are y1=Asin (ωt−kx) and y2=Asin(ωt+kx).The distance between adjacent nodes of the resulting standing wave is: " This is the question I have tried to solve. I know that the distance between two nodes is 2pii. Then I do not know how to proceed. The answer is pii/k, but I do not know how it is obtained. Please, do not hesitate to reply if you know why the answer is pii/k. Thank you in advance!