To avoid a steep descent, an airplane flying at 10,000m starts its descent 60km away from the airport. For the angle of descent to be constant, at what angle should the plane descend?

Answer 1

if the 60km is horizontal distance, then
tan x = 10/60

if it's line-of-sight distance, then
sin x = 10/60

luckily, for small x, sinx and tanx are very close to each other.