Question

помогите с алгеброй пожалуйста​

Answer 1

cos^8(165)-sin^8(165)=(cos^2(165)-sin^2(165))*(cos^4(165)+sin^4(165)-

- cos^2(165)*sin^2(165))=sqrt(3)/2*(cos^2(165)+sin^2(165))^2-

-3/4*4cos^2(165)*sin^2(165))=sqrt(3)/2(1-3/4sin^2(30))=

=sqrt(3)/2*(1-3/16)=13√3/32