Question

the greek astronomer who first measured the radius of earth reasonably accurately was:
a. archimedes.
b. eratosthenes.
c. ptolemy.
d. aristotle.

Explanation:

Eratosthenes was the Greek astronomer who calculated the Earth's circumference (from which radius can be derived) with reasonable accuracy using geometric methods and observations of shadows at different locations. Archimedes was known for work in mathematics and physics, Ptolemy for his geocentric model, and Aristotle for philosophical and scientific theories but not Earth's radius measurement.

Answer:

b. Eratosthenes.