The document calculates the instantaneous value of a wave resulting from combining a 50 Hz fundamental wave with a third harmonic wave at 0.005 seconds. The fundamental wave has a maximum value (Emax) of 339 V. The third harmonic wave has a Emax of 113 V. It finds that the fundamental wave equals 339 V at 0.005 seconds, while the third harmonic equals -113 V. It then sums these values to determine that the instantaneous voltage of the combined wave at 0.005 seconds is 226 V.