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Prove that: \ cos A+cos3A+cos5A+cos7A=4c...

Prove that: `\ cos A+cos3A+cos5A+cos7A=4cos A cos2A cos4A`

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To prove that: \[ \cos A + \cos 3A + \cos 5A + \cos 7A = 4 \cos A \cos 2A \cos 4A \] we will start by manipulating the left-hand side (LHS) using the sum-to-product identities. ...
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  2. Prove that: cos3A+cos5A+cos7A+cos 15 A=4cos4A cos5A cos6A

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  3. Prove that: \ cos A+cos3A+cos5A+cos7A=4cos A cos2A cos4A

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  17. Prove that: (sin5A cos2A-sin6A\ cos A)/(sin A\ sin2A-cos2A cos3A)=t a ...

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  18. Prove that: (sin3A cos4A-sin Acos2A)/(sin4A sin A+cos6A cos A)=tan2A

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