Final answer:
Archimedes's main interest was mathematics. He made significant contributions to geometry and engineering by applying mathematical principles.
Step-by-step explanation:
The main interest of the Hellenistic thinker Archimedes was mathematics. He was one of the most important mathematicians of his time. Archimedes made significant contributions to the field of geometry and is best remembered for his applications of geometry to engineering. He discovered the principle of using the displacement of water to calculate the specific gravity of objects. His work had a major impact on mathematics and engineering.