Question

How do you measure the circumference of the earth using sun angles?

Answer 1

This is a bit tricky...!

Explanation:

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 `theta` using your height `h` and the length of the shadow `l` as:
`theta=arctan(l/h)`
and knowing the arclength `s` you can find the radius `r` using the fact that:
`s=r*theta`
giving:
`r=s/theta`
and then use `C=2pir` for the circumference.

Hope it is understandable...