A TV transmitting antenna is 81 m tall. How much service area it can cover if the receiving antenna is at the ground level? (Radius of earth=`6.4xx10^(6)m`)

ATV transmitting antenna is 100 m tall. How much service area can it cover if the receiving antenna is at the ground level? Radius of earth is 6400km.

Television broadcast is done by space wave mode of propagation. A TV transmission antenna is 81 m tall. How much service area can it cover If the receiving antenna is at the ground level? (Radius of earth is 6400km)