Why is East Africa often called the "cradle of humanity"?
2 answers:
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Answer:
Earth circumference is 25000 miles
correct option is 25,000 miles
Explanation:
we have given here Alexandria to Syene distance = 500 miles
the sun is 1/50th of the circumference of the sky (about 7°)
as we know that Earth circumference done by astronomer Eratosthenes in 240 B.C
He observe on a particular time of day ( in noon) during the summer solstice
and there was no shadow in Syene in Egypt so This was verified that the sun must be directly on overhead and not at an angle to the surface of the city at that time
so
In Alexandria he measured the position of sun at the same time and found it to be nearly (1/50)th of a complete circle
it would be 7.2 degree (when we do = 7.2)
so 2 reference points being 2 cities for the sun
all measure circumference = the distance between these two cities × 50
and we have given 500 miles
so
Earth circumference = 500 × 50
Earth circumference is 25000 miles
correct option is 25,000 miles