If the phase angle of a circuit is 28 degrees, the power factor is approximately ___%.

To determine the power factor from a given phase angle, you use the cosine of the phase angle. The power factor is defined as the cosine of the angle between the current and voltage waveforms in an AC circuit.

In this scenario, the phase angle is 28 degrees. Calculating the cosine of 28 degrees gives you approximately 0.8829. To express this as a percentage, you multiply by 100, resulting in approximately 88.3%.

Therefore, having determined that the cosine of 28 degrees is a value that corresponds to around 88.3% reflects the efficient use of electrical power and characterizes this particular circuit's power quality. Thus, option C, which represents this value, is the correct answer.