IPA: /traɪˈæŋɡərli/
KK: /traɪˈæŋɡərli/
In a shape or manner that has three sides or angles, resembling a triangle.
The flags were arranged triangularly around the perimeter of the field.
Triangularly → It is formed from "triangulus" (Latin for triangle, meaning three-cornered) and the suffix "-ly" (meaning in a manner of). The word "triangularly" means in a manner that relates to or resembles a triangle.
Think of the shape with three corners ('triangulus') and how something can be done 'in a manner of' that shape.