Question 1105168
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find the exact value cos(n/6)cos(n/12)-sinx(n/6)sin(n/12)
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<pre>
  cos(n/6)cos(n/12)-sinx(n/6)sin(n/12) = apply the addition formula for cosine =


= {{{cos(n/6+n/12)}}} = {{{cos((2n)/12 + n/12)}}} = {{{cos((3n)/12)}}} = {{{cos(n/4)}}}. 


Next,  I assume that "n" is actually "pi" = {{{pi}}}   (n is a way how the author of the post writes {{{pi}}} )  and then  


{{{cos(n/4)}}} = {{{cos(pi/4)}}} = {{{sqrt(2)/2}}}.
</pre>