A helicopter hovers 105 m above the end of an island. If the angle from the helicopter down to the other end of the esland is 13deg30', find the length of the island.
make a diagram showing a sideview.
remember the angle of depression from the helicopter view is equal to the angle of elevation from groundview.
So I have a right-angled triangle, with a height of 105 (opposite side), the adjacent side of x and an angle of 30.5
take it from there