Speakers C and D emit the same pure tone of wavelength 1.5 m, are exactly in phase, and are 3.6 m apart. An observer begins at point P, equidistant to the two speakers, and moves directly to point Q along the path shown. Point Q is the position of the 1st loud spot (completely constructive interference) encountered after leaving point P. Point Q is _ m further from D than from C. Please help. The answer is 1.5 but I don't know how to get there because my teacher never did an example like this.