Using double-angle identities, what is cos(2θ) expressed solely in terms of sin(θ)?
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1 - 2sin²(θ)
The double-angle formula for cosine has three forms: cos²(θ) - sin²(θ), 2cos²(θ) - 1, and 1 - 2sin²(θ). These are frequently used in calculus to simplify integrals.
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- What is the form of the double-angle formula for cos(2θ) that uses only the sine function?