2arccos(-1)-1/3arccos√2/2+2arccos0

Ответ. 1.sin (2*arccos(1/3))=2*cos(arccos(1/3))*(1-(cos(arccos(1/3))^2)^0,5=2*(1/3)*(1-1/9)^0,5=(2/3)*(2/3)*2^0,5=(4/9)*2^0,5; 2. cos (2*arcsin(5/13))=1-2*(sin(arcsin(5/13))^2=1-50/169=119/169;