Edexcel A Level Maths: Pure:复习笔记5.3.1 Trigonometry - Simple Identities
Trigonometry - Simple Identities
What is a trigonometric identity?
- Trigonometric identities are statements that are true for all values of x or theta (θ)
- They are used to help simplify trig equations before solving them
- The first two identities you must know are:
Where do these identities come from?
- Although you don’t need to know the proof for these identities it is important to understand where they come from
How to use the identities
Exam Tip
- You’ll need to remember these identities as they aren’t in the formula booklet.
- If asked to show one thing is identical (≡) 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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