Trigonophobia

Trigonophobia is the fear or hatred of triangles, whether they are close together or scrambled. It is not an officially known mental disorder, but it can be diagnosed as a particular phobia if there is excessive fear and anxiety. Symptoms include (but not limited to): Sweating, anxiety, suicidal thoughts, abnormal facial expressions, vomiting, red eyes, and grinding teeth.

Etymology
The term trigonophobia comes from Greek τρίγωνο - triangle and φόβος - fear.