Meeka,

Can you draw a sketch of the situation? It should include the locations of the airplane and airport, as well as the obvious vertical and horizontal lines.

If you've drawn your sketch in the most natural way, this angle will not be an angle of your triangle but will be equal to one of them.

what is the distance from the plane to the airport measured along the ground?

You will need to use one of the trigonometric ratios here. As the side you know and the dise you want to find are at right angles, it will be a tangent.

Good Hunting!
RD

PS: I have to admit when I glanced at your title I misread it as "Angel of Depression" and my first thought was that it would make a good rock album title.