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 Question from Odukoya, a student: How can I express Sin 4A in term of Sin A?

Hi,

Write $B = 2A$ and expand $\sin 4A = \sin 2B$ using the double angle formula for $\sin 2B.$ Write this in terms of $A$ and expand $\sin 2A$ and $\cos 2A$ again using the double angle formulae. Can you complete the problem now?

Write back if you need more assistance,
Penny

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