# Trigonometry

Author:
pirsquared

## Basic Trigonometry - Key Facts

You must be familiar with the: sine rule: cosine rule:

## Trigonometric Equations - Key Facts

You must be familiar with the identities  and . A trigonometric equation of the form  has many solutions:
• a principal solution, ie.  - the one you get from your calculator;
• an alternate solution, ie.  - as cos has two solutions in each 360°;
• an infinite number of repeat solutions from , since cos repeats every 360°.
You will be asked to give the solutions in a certain interval, eg.