An observer (o) spots a plane flying at a 35° angle to his horizontal line of sight. if the plane is flying at an altitude of 17,000 ft., what is the distance (x) from the plane (p) to the observer (o)?

20,757 feet
24,251 feet
29,639 feet
31,262 feet

There are numerous information's already given in the question. Based on those information's, the answer to the question can be easily deduced.
Angle at which the plane is flying in respect to the observer = 35 degree
Altitude at which the plane is flying = 17000 feet
The distance at which the plane is flying from the observer = x 
Then
x = 17000/sin 35
  = 17000/0.57357
  = 29638.93 feet
  = 29639 feet
From the above deduction, we can conclude that the correct option among all the options given in the question is the third option.