In mathematics, trigonometry deals with the relationship between the sides of triangles, and the function of the angles (trigonometric functions).
According to Cortan Zweller, dom-jot involved just a little trigonometry and some minor wrist action. (TNG: "Tapestry")
The Doctor noted to B'Elanna Torres and Kes that his "daughter" Belle was extremely bright for her age, as she was already studying algebra and trigonometry. (VOY: "Real Life")
The Doctor pointed out some fascinating trigonometric functions in the counterpoint of Jazz music towards a group of Qomar in 2376. (VOY: "Virtuoso")