Trigonometry
posted by AwesomeGuy .
A passenger in an airplane flying at an altitude of 10 kilometers sees two towns directly to the left of the plane. The angles of depression to the towns are 28° and 55°. How far apart are the towns?

tan55o = Y/X1 = = 10km/X1
X1 = 1okm/tan55 = 7 km.
tan28o = Y/(x1+x2) = 10km/(x1+x2).
x1+x2 = 10km/tan28 = 18.8 km.
7+X2 = 18.8
X2 = 11.8 km.
d = 18.8  7 = 11.8 km = Distance bet.
the two towns.