( cos п/12-sin 12)*(cos п/12+sin п/12)

Question

( cos п/12-sin 12)*(cos п/12+sin п/12)

Answer 1

(cosπ/12-sinπ/12)(cosπ/12+sinπ/12)=
=cos²π/12-sin²π/12=cos(2*π/12)=cosπ/6=√3/2