1. **State the problem:** We need to find the total surface area of the pentagonal prism (pedestal) to determine how much tile is required to cover it.
2. **Identify the shape and dimensions:** The prism has a height of $20$ cm.
The base is a pentagon composed of:
- Two adjacent sides of $12$ cm each,
- One side of $14$ cm,
- Two small triangles on top and bottom with side length $8$ cm.
From the net, the central rectangle is $20$ cm by $14$ cm.
3. **Surface area components:**
- The lateral faces correspond to the rectangle and attached triangles.
- The two pentagonal bases (top and bottom) are congruent.
4. **Calculate the area of the rectangular face:**
$$\text{Area}_{rectangle} = 20 \times 14 = 280 \text{ cm}^2$$
5. **Calculate the area of the two large triangles on the sides:**
Each triangle has sides $12$, $12$, and $14$ cm.
Use Heron's formula:
$$s = \frac{12 + 12 + 14}{2} = 19$$
$$\text{Area} = \sqrt{s(s-12)(s-12)(s-14)} = \sqrt{19 \times 7 \times 7 \times 5} = \sqrt{4655} \approx 68.24 \text{ cm}^2$$
Two such triangles:
$$2 \times 68.24 = 136.48 \text{ cm}^2$$
6. **Calculate the area of the two small triangles on top and bottom:**
Each has base $14$ cm and height $8$ cm.
$$\text{Area} = \frac{1}{2} \times 14 \times 8 = 56 \text{ cm}^2$$
Two such triangles:
$$2 \times 56 = 112 \text{ cm}^2$$
7. **Calculate the area of the pentagonal bases:**
The base is composed of the rectangle $14 \times 20$ plus the two small triangles $56$ each.
But since the net shows the rectangle and triangles as lateral faces, the bases are pentagons formed by the sides $12$, $12$, $14$, and the small triangle parts.
We approximate the pentagonal base area as the sum of the rectangle and two small triangles:
$$280 + 112 = 392 \text{ cm}^2$$
Two bases:
$$2 \times 392 = 784 \text{ cm}^2$$
8. **Total surface area:**
Sum of lateral faces and two bases:
$$280 + 136.48 + 112 + 784 = 1312.48 \text{ cm}^2$$
9. **Final answer:**
The tile needed to cover the pedestal is approximately
$$\boxed{1312.48 \text{ cm}^2}$$
Tile Pedestal E2E7E8
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