What was the Turkish triangle in Anatolian Seljuq dome construction?

In the context of Anatolian Seljuq architecture, the "Turkish triangle" is a specific type of pendentive used to transition from a square or polygonal room to a circular dome.

Architecturally, it represents a transformation of the traditional curved pendentive space into a fanlike arrangement of long, narrow triangles. These triangles are built at an angle from each other, effectively filling the upper corners of a room to provide a structural base for the dome above.1

This technique was one of several vaulting methods employed by Anatolian builders—alongside barrel vaults, groin vaults, and squinch domes—and it played a significant role in the development of vault construction that would later become a hallmark of Ottoman architecture.1