Proving trigonometric identities

• You can use trigonometric identities you already know to prove new identities
• Make sure you know the?simple trigonometric identities?and?further trigonometric identities
• To prove an identity start on one side and proceed step by step until you get to the other side

• Clever substitution into the?compound angle formulae?can be a useful tool for proving identities

• Make sure you are confident handling fractions and fractions-within-fractions

• Always keep an eye on the 'target' expression – this can help suggest what identities to use