1) The triangle is a right-angle triangle, therefore:
Cos(60) = The distance to helicopter / distance between her and Jeremiah
1/2 = D / 4,000
D = 4,000 x 1/2
D = 2,000 ft. distance between Amanda and the helicopter.
2)
Cos(30) = Distance from Jeremiah to helicopter / 4,000
0.866 = D / 4,000
D =0.866 x 4,000
D =~ 3,464 ft -distance between Jeremiah and the helicopter.
