Expand 2 cos (2 b) using a double angle identity in terms of sines

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Expand 2 cos (2 b) using a double angle identity in terms of sines

Guest May 16, 2015

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Best Answer

+118608

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$$\\2cos(2B)\\
=2(cos^2B-sin^2B)\\
=2(1-sin^2B-sin^2B)\\
=2(1-2sin^2B)\\$$

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Melody May 17, 2015

1⁺⁰ Answers

+118608

+10

Best Answer

$$\\2cos(2B)\\
=2(cos^2B-sin^2B)\\
=2(1-sin^2B-sin^2B)\\
=2(1-2sin^2B)\\$$

Melody May 17, 2015

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