Arduino GPS bearing and distance

GPS bearing and distance computation

http://www.instructables.com/id/Distance-measuring-and-more-device-using-Arduino-a/step5/Arduino-programming/

The mean circumference of the earth is 2 x 6,371,000m x π = 40,030,170m

Δd (lat) = 40,030,170 x ΔΘ (lat) / 360 (assuming ΔΘ is small)
Δd(long) = 40,030,170 x ΔΘ(long) x cosΘm / 360 (Θm: mean latitude between two positions)
Now, the distance is √[Δd (lat)^2 Δd (long)^2]