+0  
 
+2
142
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avatar+271 

Use the half-angle formulas to simplify the expression.

 

 

sqrt((1 + cos(26x)) /2)

 Dec 2, 2018
 #1
avatar+159 
+2

The simplified answer is: −sin(x−12) cheeky

 Dec 2, 2018
 #2
avatar+99122 
+1

\(cos(2*13x)=cos^2(13x)-sin^2(13x)\\ cos(2*13x)=cos^2(13x)-(1-cos^2(13x))\\ cos(2*13x)=2cos^2(13x)-1\\ \frac{cos(2*13x)+1}{2}=cos^2(13x)\\ so\\ \frac{1+cos(26x)}{2}=cos^2(13x)\\ \sqrt{\frac{1+cos(26x)}{2}}=\sqrt{cos^2(13x)}\\ \sqrt{\frac{1+cos(26x)}{2}}=cos(13x)\\ where \quad cos(13x) \ge 0\)

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 Dec 3, 2018

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