Question 875669
let ground distance to the near end of runway be x
 rhe distance between two ends be 9000

tan17.5 =9000/(x+9000)

x+9000 = 9000/tan 17.5

x= 9000/tan 17.5 - 9000

x=19544 

cos 18.5 = 19544/ air distance to touch down

air distance to touch down = 19544/cos 18.5

=20609 feet