Сократите дробь: (a^2-12a+36)/(36-a^2).

\[\frac{a^{2} - 12a + 36}{36 - a^{2}} =\]

\[= \frac{(a + 6)^{2}}{(6 - a)(6 + a)} = \frac{a + 6}{a - 6}.\]