IB DP Maths: AI HL复习笔记3.4.2 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