Răspuns:
Explicație pas cu pas:
cos π/6=2cos²π/12-1 √3/2=2cos²π/12-1 √3=cos²π/12-2
cos²π/12=√3+2 cos π/12=√(2+√3)=√(2+1)/2+√1/2=√2(√3+1)/2
