Question 1079977
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{{{5pi/12}}} = 75° = 45° + 30° = {{{pi/4 + pi/6}}}  =====>

{{{cos(5pi/12)}}} = {{{cos(pi/4 + pi/6)}}}  = {{{cos(pi/4)*cos(pi/6) - sin(pi/4)*sin(pi/6)}}}  ====>


    Use {{{cos(pi/4)}}} = {{{sqrt(2)/2}}},  {{{cos(pi/6)}}} = {{{sqrt(3)/2}}},  {{{sin(pi/4)}}} = {{{sqrt(2)/2}}},  {{{sin(pi/6)}}} = {{{1/2}}}  ====>


= {{{(sqrt(2)/2)*(sqrt(3)/2) - (sqrt(2)/2)*(1/2)}}} = {{{sqrt(6)/4 - sqrt(2)/4}}} = {{{(sqrt(6)-sqrt(2))/4}}}.
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