(1+2sqrt(3))^2=1+2*2sqrt(3)+(2sqrt(3))^2=1+4sqrt(3)+12=13+4sqrt(3)=13+sqrt(48) ⇒ sqrt(13+sqrt(48))=sqrt((1+2sqrt(3))^2)=|1+2sqrt(3)|=1+2sqrt(3) sqrt(5-sqrt(13+4sqrt(3)))=sqrt(5-1-2sqrt(3))=sqrt(4-2sqrt(3)) слева 4, справа (-2 sqrt(3)) sqrt(4-2sqrt(3)) ≈ sqrt(4-2*1,732)=sqrt(0,536)=0,732