The maximum line of sight is calculated from the following expression as, dm=√2RhT+√2RhR Substitute the given value in the above equation. dm‌‌=√2RhT+√2RhR 40×103‌‌=√2×6.4×106×20+√2×6.4×106×x √2×6.4×106x‌‌=24000 x‌‌=45m