Verified Answer :

HomertheGenius

sin(theta) = 4/5,\(cos^{2} (theta)=1-( \frac{4}{5})^{2} = 1 - \frac{16}{25} = \frac{9}{25}\) We will switch it to formula: \(cos(2 theta)=cos^{2} (theta)-sin^{2} (theta)= \frac{9}{25} - \frac{16}{25}=- \frac{7}{25}\)

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