# Quick Mathematica help!

I type the following and it doesn't work:

DSolve[{x''[t] == (1/((Cos(2Pi*t))(x[t]^2 + y[t]^2)))(Sin(arctan(x[t]/y[t]))), y''[t] == (1/((Cos(2Pi*t))(x[t]^2 + y[t]^2)))(Cos(arctan(x[t]/y[t])))}, {y[t], x[t]}, {t}]

I want to solve for x and y in terms of t.