What is the arc length formula and how would it be used to find the radius of the earth?

1 Answer
Apr 17, 2016

If arc length (seemingly horizontal distance) between two locations on the equator, with longitude difference θo, is S km, the equatorial radius is (Sθ)(180π)km

Explanation:

The formula used is (circular arc length) = radius X (angle subtended at the center in radian)
Sample data, for explication:

If two locations, near the equator, in Brazil, have longitudes 45oWand55oW and the distance in-between is 1100 km, S = 1100 km, θ=10o.

Equatorial radius R=(110010)(180π)km= 6302 km.