wrote:

Su- I had a bit of trouble with this recently figuring out
what google earth would accept.

note about Google Map; they'll take the decimal degrees form, but
beware of the convention they use for East/West longitude: West
longitudes are expressed as a negative number (as opposed to the
frequently used opposite);

also, doing spherical trigonometry is a lot of fun (I am toying
with such applications these days), but beware of the effects
of rounding errors, the formula right off the books won't always
produce the intended results! :-)) (a classical one is to make
sure you don't feed acos or asin with numbers greater than one
or smaller than minus one -- but there are plenty of other gotchas :-)

--Sylvain