Trigonometry is the study of how the sides and angles of a triangle are related to each other. Interestingly, the angles are usually measured in terms of a circle around the *x* and *y* axes; from there, certain formulas are calculated, much as they are in algebra, to determine all the angles and units. Because trigonometry is such a mix of algebra and geometry, it is often considered “the art of doing algebra over a circle.” Although “trig” (as it is nicknamed) is a small part of geometry, it has numerous applications in fields such as astronomy, surveying, maritime and aerial navigation, and engineering.