Question

Why was the route trading ships took in the Atlantic called the triangular trade?

Answer 1

It is a historical term indicating trade among three ports or regions.
I think this is why, but hope it helps :)

Answer 2

Answer: On the first leg of their three-part journey, often called the Triangular Trade, European ships brought manufactured goods, weapons, even liquor to Africa in exchange for slaves; on the second, they transported African men, women, and children to the Americas to serve as slaves; and on the third leg, they exported to.