Pears

You can't solve a triangle unless you have these.

Pears have historically been used as gnome-repellent, especially in the ancient mythologies of Transylvania. The Gnomeyboi became a mathematician so that he could freely search for pears under the guise of solving triangles, and ultimately destroy all the pears, leaving the Incredipede order invincible and free to make sure there won't be a kid left in the school.

Gnomeyboi once found a cartoon pear on the floor of his classroom. This event shook him to the core and weakened his Incredipede Powers, and he vowed that when he finds the perpetrator, "It's gonna get gory".