Find the lateral area of a life raft in the form of a regular pentagonal pyramid if the slant height is 17 ft. and one edge of the base is 15 ft. How many persons could be accommodated if a person occupies a space of 8.5 sq. ft.? (Headbang)

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- Jan 26th 2010, 04:27 AMolokishPyramid problem
Find the lateral area of a life raft in the form of a regular pentagonal pyramid if the slant height is 17 ft. and one edge of the base is 15 ft. How many persons could be accommodated if a person occupies a space of 8.5 sq. ft.? (Headbang)

- Jan 26th 2010, 07:58 AMearboth
1. Draw a rough sketch.

2. Let e denote the edge of the base, the slant height.

Calculate the radius r of the circumscribed circle:

3. The area of a regular pentagon consists of 5 isosceles triangles with the base e and the radius as the other legs.

Divide by 8.5 to answer the question.

3. The lateral area consists of 5 isosceles triangles with the base and the height .