Ecotourists use their global positioning system indicator to determine their location inside a botanical garden as latitude 0.002 43 degree south of the equator, longitude 75.642 38 degrees west.

they wish to visit a tree at latitude 0.001 62 degree north, longitude 75.644 26 degrees west.

(a) determine the straight-line distance and the direction in which they can walk to reach the tree as follows. first model the earth as a sphere of radius 6.37 mm to determine the westward and northward displacement components required, in meters. then model the earth as a flat surface to complete the calculation.

(b) explain why it is possible to use these two geometrical models together to solve the problem