The problem asks to find the lateral area ($L$) and surface area ($S$) of a regular triangular pyramid, given the side length of the base ($b = 14$ ft) and the slant height ($l = 12$ ft). We need to round the answers to the nearest tenth, if necessary.
2025/4/14
1. Problem Description
The problem asks to find the lateral area () and surface area () of a regular triangular pyramid, given the side length of the base ( ft) and the slant height ( ft). We need to round the answers to the nearest tenth, if necessary.
2. Solution Steps
The formula for the lateral area of a regular pyramid is:
where is the perimeter of the base and is the slant height.
The base is a triangle with side length ft. The perimeter of the triangular base is:
ft.
The slant height is given as ft.
Substitute these values into the lateral area formula:
square feet.
The formula for the surface area of a regular pyramid is:
where is the lateral area and is the area of the base.
We already found square feet. Now we need to find the area of the triangular base . Since the problem stated "assume a base that appears to be a regular polygon is a regular polygon", we assume the base is an equilateral triangle.
The area of an equilateral triangle with side is:
square feet.
Now we can find the surface area:
square feet.
3. Final Answer
L ≈ 252.0
S ≈ 336.9