For which waveform are the root mean square (r.m.s.) value and the average (mean) value identical?

Explanation

Among the listed waveforms, only the square wave has equal r.m.s. and mean values. This is because the square wave maintains a constant amplitude during its cycle, causing the average magnitude and the r.m.s. value to be the same. Other waveforms like triangular, sine, and half-wave rectified sine have varying amplitudes, resulting in different r.m.s. and mean values.