Course: Trigonometry
Topic: The Six Trigonometric Functions
Subtopic: Angles


We start the course with some basic terminology and geometry primarily related to angles and triangles. Much of this you likely know from a previous geometry course so concentrate on the content that is new to you. Being familiar with all the terminology and diagrams will establish a strong foundation to the course.


By the end of this topic you should know and be prepared to be tested on:


Terms you should be able to define: degree, minute and second (in terms of angles not time), DMS measure, decimal degree measure, right angle, straight angle, acute angle, obtuse angle, complementary angles, supplementary angles, coterminal angles, quadrantal angles

Be familiar with the circle diagram which indicates all the "nice angles" at 30°, 45°, 60°, 90°, etc.

Circle diagram with degree angles 30, 45, 60, etc. spinning counter-clockwise around the circle to 360 degrees.

Mini-Lectures and Examples

STUDY: Angles, Triangles, and the xyr Definition of Trig Functions

Supplementary Resources (recommended)

Watch Trigonometry, part of a BBC show for a very brief entertaining introduction to Trig.

Reading What is Trigonometry? and What is Trigonometry All About? are both recommended to get the "big picture" of this course and how Trig is used in real world applications.

Know how to write at least the first 5 letters of the Greek alphabet.

Supplemental Resources (optional)

Skimming History of Trigonometry Outline provides a brief overview of some of the theorems and characters involved in the development of Trigonometry.

Videos from James Sousa's MathIsPower4U:

Mini-Lesson: Angle Basics
Animation: Types of Angles
Mini-Lesson: Angles in Standard Position
Animation:  Angles in Standard Position

Determine Angles of Rotation
Determine if Two Angles Are Coterminal
Determine a Coterminal Angle Between 0 and 360 Degrees
Determine Positive and Negative Coterminal Angles

rev. 2021-04-05