a) \(\left(\sqrt{2-\sqrt{3}}-\sqrt{2+\sqrt{3}}\right)^2\)
\(=\left(\sqrt{2-\sqrt{3}}\right)^2-2\sqrt{2+\sqrt{3}}.\sqrt{2-\sqrt{3}}+\left(\sqrt{2+\sqrt{3}}\right)^2\)
\(=2-\sqrt{3}-2\sqrt{\left(2+\sqrt{3}\right)\left(2-\sqrt{3}\right)}+2+\sqrt{3}\)
\(=4-2\sqrt{1}\)
\(=2\)