1. The problem statement, all variables and given/known data The figure shows the displacement y versus time t of the point on a string at x = 0, as a wave passes through that point. The scale of the x axis is set by ys = 84.0 mm.The wave has form y(x, t) = ym sin (kx - ωt+φ). What is φ? (Caution: A calculator does not always give the proper inverse trig function, so check your answer by substituting it and an assumed value of ω into y(x, t) and then plotting the function.) 2. Relevant equations y(x, t) = ym sin (kx - ωt+φ) 3. The attempt at a solution This is supposed to be really easy but the solution I got was wrong. My approach was straight forward: read off the initial y value --- y(0,0)=0.028 and sub in the equation: 0.028=0.084sin(0-0+φ) φ=arcsin(0.028/0.084)=0.339836.......=0.340 rad The question mentioned that the calculator might give the wrong value but I do not see how I could make amend to it. Please enlighten me!