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Math Help - Indentity for cos^2a clarification

  1. #1
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    Indentity for cos^2a clarification

    I have this equation: y(t)=[A+m(t)]cos^2(wt)

    I going to use the power reduction identity cos^2a=(1+cos2a)/2

    I'm not sure how to handle the coefficient [A+m(t)], is a more general form of the identity: Bcos^2(a)=(B+Bcos2a)/2

    So my solution would be?

    y(t)=[A+m(t)]/2 + [A+m(t)]cos^2(wt)/2

    If someone could clarify this, I would appreciate it, thanks.
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  2. #2
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    \displaystyle y(t)=(A+m(t))\cos^2(wt)

    \displaystyle \cos^2(wt) = \frac{1+\cos(wt)}{2}

    so \displaystyle y(t)=(A+m(t))\cos^2(wt) = (A+m(t))\times \frac{1+\cos(wt)}{2}

    \displaystyle y(t) = \frac{(A+m(t))\times +(A+m(t))\cos(wt)}{2}=\dots
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