Impedance in sine DC
Capacitors and inductors always have impedance, at all frequencies, including 0 which is DC.
There is no DC sine. At DC, frequency is 0, so capacitor has impedance of infinity so it is an open circuit and inductance has impedance of zero so it is a short circuit. AC signal has a frequency, and ideal square wave consists of harmonic frequencies up to infinity, so yes, capacitors and inductors have impedance at all frequencies.
Recitified AC is also AC, even if it has an average DC component.