Answer:
18
Step-by-step explanation:
The hypotenuse is BC.
According to the Pythagorean Theorem;
[tex]BC^2=AC^2+AB^2[/tex]
Since the base angles are equal:
[tex]AC=BC=9\sqrt{2}[/tex]
We substitute the given values into the formula to obtain:
[tex]BC^2=AC^2+AB^2[/tex]
[tex]BC^2=(9\sqrt{2})^2+(9\sqrt{2})^2[/tex]
[tex]BC^2=81(2)+81(2)[/tex]
[tex]BC^2=162+162[/tex]
[tex]BC^2=324[/tex]
Take positive square root.
[tex]BC=\sqrt{324}[/tex]
[tex]BC=18[/tex]
Hence the hypotenuse is 18 units