1. Introduction to trigonometry

2. What is trigonometry?
The branch of mathematics called trigonometry deals with the relationship between the side lengths and angles in triangles.

3. Trigonometry dates back to the ancient Egyptian and Babylonian civilizations where a basic form of trigonometry was used in building the pyramids and also in the study of astronomy!

4. Some important features we will have to know
The hypotenuse is the longest side and is always opposite the 90° angle
The opposite side is opposite the angle (theta)
The adjacent side is next to the angle (theta)

5. The trigonometric ratios

6. Here is a useful way of remembering the three ratios

7. Examples

8. Cambridge exercises Chapter 3E Trigonometric Ratios
Questions 1, 2a –d , 3, 4a, c, e, h
5 a, b
6 a – c
8 & 9

9. Homework
CAMBRIDGE EXERCISE 3E
2e – h
4b, d, f, g 5c
7a – c