\[ \left \{x''(t)=a e^{2 x(t)}+e^{-2 x(t)} \cos ^2(y(t))-e^{-x(t)},y''(t)=e^{-2 x(t)} \sin (y(t)) \cos (y(t))-\tan (y(t)) \sec ^2(y(t))\right \} \] ✗ Mathematica : cpu = 0.0099291 (sec), leaf count = 0 , could not solve
DSolve[{Derivative[2][x][t] == -E^(-x[t]) + a*E^(2*x[t]) + Cos[y[t]]^2/E^(2*x[t]), Derivative[2][y][t] == (Cos[y[t]]*Sin[y[t]])/E^(2*x[t]) - Sec[y[t]]^2*Tan[y[t]]}, {x[t], y[t]}, t]
✗ Maple : cpu = 0. (sec), leaf count = 0 , could not solve
dsolve({diff(diff(x(t),t),t) = a*exp(2*x(t))-exp(-x(t))+exp(-2*x(t))*cos(y(t))^2, diff(diff(y(t),t),t) = exp(-2*x(t))*sin(y(t))*cos(y(t))-sin(y(t))/cos(y(t))^3})