Reduce with inverse trig functions


    c = 5.; b = 3.; a = 2.; len = 7.5; u[t_] := Reduce[   NSolve[(2 c + a Cos[t] - b Cos[u])^2 + (a Sin[t] - b Sin[u])^2 -       len^2 == 0], u, Reals] Plot[u[t], {t, 0, 2 Pi}] 

Please help to obtain a simplified output using Reduce.