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

1 Answer
Feb 1, 2016

Answer:

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.
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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...