Use the formula for the surface area of a square pyramid to solve for the slant height if the length of the base is 40 in. and S A equals 2,800 in^2.

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

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

The base area of a square pyramid is given by the formula:

Base Area = (Length of Base)^2

Given that the length of the base is 40 inches, the base area can be calculated as:

Base Area = (40)^2 = 1600 square inches

Substituting the given values into the surface area formula:

2800 = 1600 + (1/2) * Perimeter of Base * Slant Height

We need to find the perimeter of the base in order to solve for the slant height. Since it is a square pyramid, the perimeter of the base is given by:

Perimeter of Base = 4 * Length of Base

Substituting the length of the base:

Perimeter of Base = 4 * 40 = 160 inches

Now we can solve the equation:

2800 = 1600 + (1/2) * 160 * Slant Height

Subtracting 1600 from both sides:

2800 - 1600 = (1/2) * 160 * Slant Height

1200 = 80 * Slant Height

Dividing both sides by 80:

1200/80 = Slant Height

15 = Slant Height

Therefore, the slant height of the square pyramid is 15 inches.