Comments on: Trigonometry?

By: Anonymous

Anonymous — Fri, 24 Jul 2009 02:58:47 +0000

Draw a circle.
On the right half of the circle put two different dots. The upper dot is Syracuse and the lower is Annapolis. (Obviously, this won’t be to scale.)
Label the arc between them 450km.
Draw the radii to the dots and label them 6378km.
Determine the central angle ?:
? = arclength×180/(?r)
= 450×180/(?6378)
= 4°
If you want to see the drawing, go to my profile and click on the Photobucket link.

By: Dennis W

Dennis W — Thu, 23 Jul 2009 23:37:50 +0000

The central angle in radians is the surface distance divided by the earth radius.
Therefore, the angle subtended by the two cities at the earth center is
ang = 450/6378 radians.
This is the latitude difference since the cities are at the same longitudes (nort/south of each other)

By: Philo

Philo — Thu, 23 Jul 2009 22:20:10 +0000

450/(2?•6378) = 0.0112 of circumference =
0.0112 of 360° =
4.0425°