\(\sqrt{6-2\sqrt{\sqrt{2}+\sqrt{12}+\sqrt{18-8\sqrt{2}}}}\)
= \(\sqrt{6-2\sqrt{\sqrt{2}+\sqrt{12+\sqrt{\left(4-\sqrt{2}\right)^2}}}}\)
= \(\sqrt{6-2\sqrt{\sqrt{2}+\sqrt{12}+4-\sqrt{2}}}\)
= \(\sqrt{6-2\sqrt{4+2\sqrt{3}}}\)
= \(\sqrt{6-2\sqrt{\left(\sqrt{3}+1\right)^2}}\)
= \(\sqrt{4-2\sqrt{3}}\)
= \(\sqrt{\left(\sqrt{3}-1\right)^2}\)
= \(\sqrt{3}-1\)