dsolve({diff(x1(t),t)*sin(x2(t)) = x4(t)*sin(x3(t))+x5(t)*cos(x3(t)), diff(x3(t),t)+diff(x1(t),t)*cos(x2(t)) = a, diff(x4(t),t)-(1-lambda)*a*x5(t) = -m*sin(x2(t))*cos(x3(t)), diff(x5(t),t)+(1-lambda)*a*x4(t) = m*sin(x2(t))*sin(x3(t)), diff(x2(t),t) = x4(t)*cos(x3(t))-x5(t)*sin(x3(t))})