+23246 I don't see any direct way to find AC.
We can find angle(C), then use this answer to find angle(B), and then use the Law of Sines to find AC.
sin(C) / 8.2 = sin(81) / 13,5
sin(C) = sin(81) / 13.5 x 8.2
sin(C) = 0.59993
C = sin-1(0.59993)
C = 36.865
angle(B) = 180 - 81 - 36.865 = 62.135
AC / sin(62.135) = 13.5 / sin(81)
AC = 13.5 / sin(81) x sin(62.135)
AC = 12.1
