Trigonometry is a branch of mathematics that deals with the ratios and relationships between the sides and angles of a right triangle. In geometry, you can use trigonometry to solve problems involving right triangles. Given information on angles and sides, you can calculate the values for the remaining sides and/or angles.
There are six core trigonometric functions. In this topic, you will study the three primary ones: sine, cosine, and tangent. The remaining three functions are not used as often and are derived from the primary ones. Therefore, a solid understanding of the primary trigonometric functions lends itself to an understanding of the remaining three.
Essential Questions
- How can you use trigonometric formulas to solve for sides in a right triangle?
- How can you use inverse trigonometric formulas to solve for angles in a right triangle?
Warm-Up

Mnemonic devices are memory aids that help you recall useful information, such as a rhyme or acronym. In this topic, you will learn a mnemonic in the form of an acronym. How many mnemonic acronyms do you already use? In this non-graded interactivity, test your knowledge about mnemonic devices used in various subjects of study. Click the player button to get started.