we know that $\displaystyle cos^2(x) = 1/2(1+cos(2x))$ could I say that $\displaystyle cos^2(3x)=1/2(1+cos(6x)) $ ?
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Originally Posted by doomgaze we know that $\displaystyle cos^2(x) = 1/2(1+cos(2x))$ could I say that $\displaystyle cos^2(3x)=1/2(1+cos(6x)) $ ? Difinetly you can say so.
Originally Posted by sa-ri-ga-ma Difinetly you can say so. I guess more importantly is it correct?
Yes. --Kevin C.
Originally Posted by doomgaze I guess more importantly is it correct? If 3x= t 6x= 2t. cos(2t) = 2cos^2(t) - 1 so 2cos^2(t) = 1+cos(2t) cos^2(t) = 1/2(1+cos(2t)) replace t by 3x and find the result.
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