Answer:
[tex]AB=5\sqrt{15}\ units[/tex]
Step-by-step explanation:
we know that
In the right triangle ABC
we have
[tex]AC=20\ units[/tex] ----> is the hypotenuse
[tex]BC=5\ units[/tex] ----> is a leg
[tex]AB=?\ units[/tex] ----> is a leg
see the attached figure to better understand the problem
Applying the Pythagorean Theorem
[tex]AC^2=AB^2+BC^2[/tex]
substitute the given values
[tex]20^2=AB^2+5^2[/tex]
solve for AB
[tex]AB^2=20^2-5^2[/tex]
[tex]AB^2=375[/tex]
[tex]AB=\sqrt{375}\ units[/tex]
simplify
we know that
[tex]375=(25)(15)=5^2(15)[/tex]
substitute
[tex]AB=\sqrt{5^2(15)}\ units[/tex]
[tex]AB=5\sqrt{15}\ units[/tex]