f)
[tex](3\sqrt{5})^2+x^2=7^2\\45 + x^2=49\\x^2=49-45\\x^2=4\\x=\sqrt{4}[/tex]
e)
[tex]6^2+4^2=x^2\\36+16=x^2\\x^2=52\\x=\sqrt{52} \\x=2\sqrt{13}[/tex]
f)
[tex]x^2+(2\sqrt{5})^2=(2\sqrt{19})^2\\x^2+20=76\\x^2=76-20\\x^2=56\\x^2=\sqrt{56}\\x=2\sqrt{14}[/tex]