Digital television broadcast towers F and G are 257 m apart. Tower F is located left of tower G. Their antennas radiate in phase at the same frequency. A TV antenna is located at point H, 1 km to the right of antenna G on the axis connecting the two antennas. TV networks broadcast at various frequencies called channels. Assuming a channel can have any frequency, and similarly, the wavelength, determine the longest wavelength of a channel that will cause destructive interference at point H.