The correct equation using the Pythagorean Theorem for the given triangle, assuming the lengths of the legs are 9 and 12 (with \( c \) being the hypotenuse), is:
\[ 9^2 + 12^2 = c^2 \]
So the closest response that reflects this is:
\( 9^2 + 12^2 = c^2 \)