2.1.21.4 ✓ Mathematica. Time used: 0.049 (sec). Leaf size: 17

ode=D[x[t],t]-x[t]*Tan[t]==4*Sin[t]; 
ic={}; 
DSolve[{ode,ic},x[t],t,IncludeSingularSolutions->True]
 

\begin{align*} x(t)&\to \sec (t) (-\cos (2 t)+c_1) \end{align*}