Answer:
[tex]16[/tex]
Step-by-step explanation:
In a right triangle, the Pythagorean Theorem goes as follows:
[tex]a^2+b^2=c^2[/tex], where [tex]c[/tex] is the hypotenuse of the triangle and [tex]a[/tex] and [tex]b[/tex] are legs of the triangle.
We can set up the following equation using the information given:
Let [tex]x[/tex] be the missing side:
[tex]12^2+x^2=20^2,\\144+x^2=400,\\x^2=256,\\x=\boxed{16}[/tex]
