(a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ac=0 -> ab+bc+ac=-1/2;
(ab+bc+ac)^2=a^2b^2+b^2c^2+a^2c^2+2a^2bc+2ab^2c+2abc^2=1/4 => a^2b^2+b^2c^2+a^2c^2=1/4 - 2abc(a+b+c)=1/4
(a^2+b^2+c^2)^2=...