The solution has the form
ConditionalExpression[something +2Pi*C[1],
Element[C[1], Integers]]
which means that the expression something +2Pi*C[1]
is a solution provided that C[1]
is an integer. Try replacing C[1]
with numbers:
sol = Solve[(Cos[f] Cos[b] + Sin[f] Cos[v]) Cos[d] Cos[x] +
Cos[d] Sin[x] Sin[b] Sin[v] +
Sin[d] (Sin[f] Cos[b] - Cos[f] Sin[f] Cos[v]) == 0, x];
sol /. C[1] -> 1
sol /. C[1] -> 1/2