Question 1079117
.
<pre>
There are two possibilities.


1.  The third side, x, is the hypotenuse.

     Then x = {{{sqrt(9^2 + 12^2)}}} = {{{sqrt(215)}}} = 15.



2.  The third side is the leg.

    In this case 12 is the longest side (the hypotenuse), and the third side length is

    x = {{{sqrt(12^2 - 9^2)}}} = {{{sqrt(63)}}}.
</pre>