1. The problem statement, all variables and given/known data When completing this problem I am able to find a value for the phase angle but am unsure of how to find the quadrant for the phase angle therefore unable to get the correct phase angle. 2. Relevant equations Provided in the question: x = xmcos(wt+ phi) 3. The attempt at a solution After doing a series of calculations I determined sin(phi) = -0.8 at t =0 v(0) = -xmwsin(w(0) + phi) v(0) = -vmsin(phi) 4.0cm/s = (-5.0 cm/s)sin(phi) sin(phi) = -4/5 = -0.80 Therefore, one answer is -0.93 rad for the phase angle, phi. However other phase angles would also make sin(phi) = -0.8 such as -2.21. How do I determine which angle in radians is correct?