1. **Problem statement:** We need to find the volume of a frustum formed by removing a smaller rectangular-based pyramid from a larger similar pyramid.
2. **Given data:**
- Larger pyramid base dimensions: 45 cm by 30 cm
- Larger pyramid height: 10 cm
- Smaller pyramid base dimensions: 6 cm by 6 cm
- Smaller pyramid height: 10 cm
3. **Important note:** The smaller pyramid is similar to the larger one, so the ratio of corresponding linear dimensions is constant.
4. **Step 1: Calculate the volume of the larger pyramid.**
The volume formula for a pyramid is:
$$V = \frac{1}{3} \times \text{base area} \times \text{height}$$
Base area of larger pyramid:
$$45 \times 30 = 1350 \text{ cm}^2$$
Volume of larger pyramid:
$$V_{large} = \frac{1}{3} \times 1350 \times 10 = 4500 \text{ cm}^3$$
5. **Step 2: Find the scale factor between the smaller and larger pyramid.**
Since the pyramids are similar, the ratio of corresponding sides is the same.
We can use the base lengths to find the scale factor $k$:
$$k = \frac{6}{45} = \frac{2}{15}$$
6. **Step 3: Calculate the height of the smaller pyramid using the scale factor.**
Since the height scales the same way:
$$h_{small} = k \times h_{large} = \frac{2}{15} \times 10 = \frac{20}{15} = \frac{4}{3} \approx 1.333 \text{ cm}$$
7. **Step 4: Calculate the volume of the smaller pyramid.**
Base area of smaller pyramid:
$$6 \times 6 = 36 \text{ cm}^2$$
Volume of smaller pyramid:
$$V_{small} = \frac{1}{3} \times 36 \times \frac{4}{3} = \frac{1}{3} \times 36 \times 1.333 = 16 \text{ cm}^3$$
8. **Step 5: Calculate the volume of the frustum.**
The frustum volume is the volume of the larger pyramid minus the volume of the smaller pyramid:
$$V_{frustum} = V_{large} - V_{small} = 4500 - 16 = 4484 \text{ cm}^3$$
**Final answer:**
The volume of the frustum is **4484 cm³**.
Frustum Volume A41252
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