Use the Pythagorean theorem. We have legs with lengths of 15 and 20 miles, now let's solve for the hypotenuse.
[tex]a=15[/tex]
[tex]b=20[/tex]
[tex]c=?[/tex]
[tex]a^2+b^2=c^2[/tex]
[tex]15^2+20^2=c^2[/tex]
[tex]c^2=400+225=625[/tex]
[tex]c=25[/tex]
Your answer is 25 miles. Hope this helps! :)
