The roof and sides of the shed are covered with plastic siding. the door, which is 5 feet wide, is made with a different material. how many square feet get covered with the plastic siding?

It is 4 square feet why because of the four squares on the 5 ft wide door

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.