triangle – el triángulo
(Pronounced tree-ahn-goo-loh)
To remember that triangle is pronounced tree-ahn-goo-loh (triángulo) in Spanish, use the following mnemonic:
Flying in a triangle above the treetops, the anxious goose thought they were too low (triángulo)
Triángulo is masculine so it's el triángulo. Imagine some elephants arranged in a triangle.