Question

cos^4 5П/12-sin^4 5П12 решите, пожалуйста

Answer 1

cos^25П/12-sin^25П/12=cos5П/6=cos(П-П/6)=-cosп/6=-(√3)/2

Answer 2

$cos^4 frac{5pi}{12}-sin^4 frac{5pi}{12}=cos^22*frac{5pi}{12}=cos^2frac{5pi}{6}=cos^2frac{5*180}{6}=cos^2150к=cos^2(180к-30к)=cos^2(-30к)=frac{sqrt{3}}{2}$