Ok, here we have a right triangle, so we can use the Pythagoras theorem, so let's do it:
[tex]65^2=25^2+x^2[/tex]
And we need to clear x:
[tex]4225=625+x^2[/tex][tex]4225-625=x^2[/tex][tex]x^2=3600[/tex][tex]x=\sqrt[]{3600}[/tex][tex]x=60[/tex]
x is equal to 60 units.
