The roof of a gazebo is in the shape of an octagonal pyramid. Each side of the octagon is 12 feet, the height of each triangular face is 10 feet, and the area of the octagon is 695 square feet. How many square feet of cedar are needed to cover the lateral surface area of the octagonal pyramid?

Responses

1,175 ft.2
1,175 ft. squared

480 ft.2
480 ft. squared

960 ft.2
960 ft. squared

360 ft.2
Thank you.

1 answer

To find the lateral surface area of the octagonal pyramid, we need to calculate the area of the triangular faces first.

  1. Determine the number of triangular faces: Since the base of the pyramid is an octagon, there will be 8 triangular faces.

  2. Calculate the area of one triangular face: The area of a triangular face can be calculated using the formula: \[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} \] The base of each triangular face is equal to one side of the octagon (12 feet) and the height is given as 10 feet.

    \[ \text{Area of one triangular face} = \frac{1}{2} \times 12 \times 10 = 60 \text{ ft}^2 \]

  3. Calculate the total area of all triangular faces: Since there are 8 triangular faces, the total lateral surface area (LSA) is: \[ \text{Total LSA} = 8 \times \text{Area of one triangular face} = 8 \times 60 = 480 \text{ ft}^2 \]

Thus, the total lateral surface area of the octagonal pyramid is 480 square feet.

The correct answer is: 480 ft.²