IB DP Maths: AI HL复习笔记3.4.2 Simple Identities
Simple Identities
What is a trigonometric identity?
They are used to help simplify trigonometric equations before solving them- Sometimes you may see identities written with the symbol ≡
- This means 'identical to'
What trigonometric identities do I need to know?
Where do the trigonometric identities come from?
- You do not need to know the proof for these identities but it is a good idea to know where they come from
How are the trigonometric identities used?
- Most commonly trigonometric identities are used to change an equation into a form that allows it to be solved
- They can also be used to prove further identities such as the double angle formulae
Exam Tip
- If you are asked to show that one thing is identical (≡) to another, look at what parts are missing – for example, if tan x has gone it must have been substituted
Worked Example
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