Prove that cos 4x = 1 – 8sin^2 x cos^2 x

Question

Prove that cos 4x = 1 – 8sin² x cos² x

Monjur Alahi

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2025-01-04 04:42

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Salim Ahmed Kawsar · Accepted Answer · 2023-02-05T15:29:48+06:00

Salim Ahmed Kawsar

L.H.S=COS4x

R.H.L=1-8sin²x cos²x

=1-2(2sinx cosx)²

=1-2sin²2x

=cos4x. (1-2sin²x=cos2x)

L.H.L=R.H.L

4 views Answered 2023-02-05 15:29