Introduction to Trigonometry

Trigonometry’ derives from the Greek, meaning literally ‘triangle measuring’. Because ‘trigonometry’ is such a long word, people often informally abbreviate it as ‘trig’. The tools developed in trigonometry complement and expand those developed in geometry. For example, geometry's ‘ASA’ (angle-side-angle) congruence theorem states that a unique triangle is formed by two angles and the included side. But what are the lengths (measures) of those remaining two sides? Trigonometry gives the answer. Trigonometry is used heavily in calculus (e.g., related rate problems and integration techniques), which is why it comprises a large part of any precalculus course.Trigonometry is used in astronomy, navigation, architecture and land-surveying. The trigonometric functions are invaluable in studying any periodic (repetitive) phenomena. Love your cell phone and music CDs? Signal processing, noise cancellation, and music coding all use trigonometry.