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3. Above are pictures of a regular pyramid and prism, both with square bases. One side of the

base of the pyramid has a length of 10 inches, one side of the base of the prism has a length of
10 inches, both solids have a height of 12 inches. The pyramid has a slant height of 13 inches.
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a. Which one has the larger surface area and by how much?
b. Which has the larger volume and by how much?

User Aatishk
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1 Answer

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Let's calculate the surface area and volume for both the pyramid and the prism and compare the results.

a. Surface Area:

The surface area of a regular pyramid is given by the formula:

SA_pyr = Base Area + (1/2) * Perimeter of Base * Slant Height

The base area of the pyramid is the area of a square, which is equal to one side length squared:

Base Area_pyr = (10 inches)² = 100 square inches

The perimeter of the base is the sum of all four sides:

Perimeter of Base_pyr = 4 * 10 inches = 40 inches

Plugging the values into the formula, we have:

SA_pyr = 100 square inches + (1/2) * 40 inches * 13 inches
SA_pyr = 100 square inches + 20 inches * 13 inches
SA_pyr = 100 square inches + 260 square inches
SA_pyr = 360 square inches

Now, let's calculate the surface area of the prism. The surface area of a prism with a square base is given by the formula:

SA_prism = 2 * Base Area + Perimeter of Base * Height

The base area of the prism is the area of a square, which is equal to one side length squared:

Base Area_prism = (10 inches)² = 100 square inches

Plugging the values into the formula, we have:

SA_prism = 2 * 100 square inches + 40 inches * 12 inches
SA_prism = 200 square inches + 480 square inches
SA_prism = 680 square inches

Therefore, the pyramid has a surface area of 360 square inches, and the prism has a surface area of 680 square inches.

The prism has a larger surface area by:
680 square inches - 360 square inches = 320 square inches.

b. Volume:

The volume of a regular pyramid is given by the formula:

V_pyr = (1/3) * Base Area * Height

Plugging the values into the formula, we have:

V_pyr = (1/3) * 100 square inches * 12 inches
V_pyr = 400 cubic inches

The volume of a prism with a square base is given by the formula:

V_prism = Base Area * Height

Plugging the values into the formula, we have:

V_prism = 100 square inches * 12 inches
V_prism = 1200 cubic inches

Therefore, the pyramid has a volume of 400 cubic inches, and the prism has a volume of 1200 cubic inches.

The prism has a larger volume by:
1200 cubic inches - 400 cubic inches = 800 cubic inches.

To summarize:

a. The prism has a larger surface area by 320 square inches.
b. The prism has a larger volume by 800 cubic inches.
User Kaffarell
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