1. **State the problem:** We need to find the perimeter of the trapezoidal base of the prism. 2. **Identify the trapezoid sides:** The trapezoid has two parallel sides of length 12 each, and two non-parallel sides of length 4 each. 3. **Formula for perimeter of trapezoid:** $$\text{Perimeter} = \text{sum of all sides}$$ 4. **Calculate the perimeter:** $$\text{Perimeter} = 12 + 12 + 4 + 4$$ 5. **Simplify:** $$\text{Perimeter} = 24 + 8 = 32$$ 6. **Interpretation:** The height of the prism (9) is not part of the trapezoid perimeter; it is the length connecting the two trapezoidal bases. **Final answer:** The perimeter of the trapezoidal base is **32**.