text: The phase angle is the displacement of the wave (Delta) from it's normal position corresponding to Delta=0.  For example if \nthe solution is the form Acos(wt)+Bsin(wt) then it can be rewritten in the form Rcos(wt-Delta) where R=(A^2+b^2)^.5 and tan(delta)=B/A and w^2=k/m