29.
[tex](4\sqrt5)^2+(2\sqrt3)^2=c^2\\16*5+4*3=c^2\\80+12=c^2\\c^2=92\\\\(2\sqrt5)^2+x^2=c^2\\4*5+x^2=92\\20+x^2=92\\x^2=92-20\\x^2=72\\x=\sqrt{72}=\sqrt{36*2}=6\sqrt2[/tex]
