Introduction
Our discussion so far has been limited to right-angled triangles where, apart from the right-angle itself, all angles are necessarily less than . We now extend the definitions of the trigonometric functions to any size of angle, which greatly broadens the range of applications of trigonometry.
Prerequisites
- have a basic knowledge of the geometry of triangles
Learning Outcomes
- express angles in radians
- define trigonometric functions generally
- sketch the graphs of the three main trigonometric functions:
Contents
1 Trigonometric functions for any size angle1.1 The radian
2 General definitions of trigonometric functions
2.1 The sine and cosine of an angle
2.2 Sine and cosine in the four quadrants
3 Graphs of trigonometric functions
3.1 Graphs of sin and cos
3.2 The graph of
4 Engineering Example 4
4.1 Optical interference fringes due to a glass plate