cos 5П/12 — cos П/12+sin (arccos 1/2) Помогите пожалуйста

cos 5П/12 — cos П/12+sin (arccos 1/2)=2sinП/4sin (-П/3)+sin (+-П/3)=1)=-2*sqrt (2) /2*sqrt (3) /2+sqrt (3) /2=sqrt (3) /2 (1-sqrt (2) 2)=-2*sqrt (2) /2*sqrt (3) /2-sqrt (3) /2=-sqrt (3) /2 (1+sqrt (2)