Question 1090048

{{{256cos^6(pi/15)-384cos^4(pi/15)-32cos^3(pi/15)+144cos^2(pi/15)+24cos(pi/15)}}}
evaluate each cos 

={{{256*  0.875843203-384*0.9154140546-32*0.9358649491441+144*0.956772728821300448+24*0.978147601}}}
={{{4.000000003256064512}}}
={{{4}}}