Two waves are traveling in opposite directions on the same string. The displacements caused by the individual waves are given by y1 = (21.8 mm)sin(9.00?t - 1.25?x) and y2 = (38.4 mm)sin(2.88?t + 0.400?x). Note that the phase angles (9.00?t - 1.25?x) and (2.88?t + 0.400?x) are in radians, t is...