How do you measure the circumference of the earth using sun angles?
This is a bit tricky...!
You need two spots on the surface of the Earth, A and B.
When standing at A you produce a shadow while standing at B (at the same hour of the day, say, midday) you do not produce a shadow.
You can evaluate, from trigonometry, the angle
and knowing the arclength
and then use
Hope it is understandable...