The diagram representing this scenario is shown below
From the triangle,
A represents the plane
angle of depression = angle CAD = 47 degrees
since line AD is parallel to line BC and AC is a transversal, it means that angle BCA = angle CAD = 47 degrees because they are alternate angles(they are in similar positions and lie on the alternate sides of the transversal)
AB is the height of the plane above the ground
C represents the control tower
Thus, BC is the distance from the control tower to the position directly beneath the plane. Since triangle ABC is a right triangle, taking angle C as the reference angle,
AB = opposite side
BC = adjacent side
We would find BC by applying the tangent trigonometric ratio which is expressed as
tan # = opposite side/adjacent side
Thus,
tan 47 = 700/BC
BC = 700/tan47
BC = 652.8
The distance is 652.8 feet