Explanation:

Let the two parallel sides of the trapezium be x cm and y cm.

Then, x-y = 8     ...........(i)

1/2 × (x+y)×12 = 360

(x+y) = (360×2)/12

x+y = 60    ...........(ii)

Solving (i) and (ii) we get x =34 and y = 26

So, the two parallel sides are 34cm and 26cm.