a]
[tex]x^2=3^2+8^2\\\\x^2=9+64\\\\x^2=73\\\\\huge\boxed{x=\sqrt{73}}[/tex]
b]
[tex]y^2=(2\sqrt{17})^2-2^2\\\\y^2=2^2\cdot(\sqrt{17})^2-4\\\\y^2=4\cdot17-4\\\\y^2=68-4\\\\y^2=64\\\\y=\sqrt{64}\\\\\huge\boxed{y=8}[/tex]
c]
[tex]z^2=8^2-(12:2)^2\\\\z^2=64-6^2\\\\z^2=64-36\\\\z^2=28\\\\z=\sqrt{28}\\\\\huge\boxed{z=2\sqrt7}[/tex]
