An observer (o) spots a bird flying at a 55° angle from a line drawn horizontal to its nest. if the distance from the observer (o) to the bird (b) is 15,000 ft., how far is the bird (b) from its nest (n)? round to the nearest whole number. a right triangle b n o is shown with angle b marked 55 degrees, side b n marked x and side b o marked 15000 feet. 8604 feet 12,287 feet 18,366 feet 21,422 feet

I am assuming that since the triangle is named BNO, that N is the right angle.  The math works out if N is the right angle, B is the other base angle, and N is the vertex angle.  That means that "side" BO is actually the hypotenuse.  We are looking for the base length, BN.  55 degrees is the reference angle and sinde BN is adjacent to it, so along with that side and the hypotenuse, we will be using the cos ratio.  and 15000cos(55)=x. Solving for x we get x = 8603.6 or 8604 rounded.  First choice above.

Letter a i would say