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 .