Pythagoras' Theorem
[tex]c^{2} =\sqrt{a^{2}+b^{2}}[/tex]
a = 5
b = 7
[tex]c^{2} =\sqrt{5^{2}+7^{2}}[/tex]
[tex]c^{2} =\sqrt{25+49}[/tex]
[tex]c^{2} =\sqrt{74}[/tex]
c = 8.6 to 1d.p.
The distance is 8.6 units
see the image