To approach the runway, a pilot of a small plane must begin a 10° descent starting from a height of 1983 feet above the ground. to the nearest tenth of a mile, how many miles from the runway is the airplane at the start of this approach?

The ratio of vertical distance to horizontal distance is the tangent of the angle.
  tan(10°) = (1983 ft)/(horizontal distance in ft)
Then
  (horizontal distance in ft) = (1983 ft)/(tan(10°)) ≈ 11,246.15 ft
The horizontal distance in miles is found using the appropriate conversion.
  (horizontal distance in mi) = (horizontal distance in ft)*(1 mi)/(5280 ft)
  = 11,246.15/5280 mi ≈ 2.129953... mi

The airplane is approximately 2.1 miles from the end of the runway.