Both formulas are equivalent. The 2nd one is more visible.
I visited two pages of "Haversine formulas", all bloody wrong.
If you are given ONE apple and two worms chating together at
a calculated arc length distance in radian, you will surely
imagine to multiply by 2*π*R to tell them how long Dady worm
must travel to kiss Momy worm, given R radius of the apple.
But none of the web pages I visited. Some of the coding would
make a stone grow wings to fly away of the flat Web Earth.

Angle Haversine Earth Distance.sm (17,57 KiB) scaricato 1512 volta(e).