find the surface area of the pyramid.\nthe surface area of the pyramid is (square) in². (type a whole number.)

Explanation:

Step 1: Calculate the base area

The base is a square with side length 18 in.
$$\text{Base Area} = 18 \times 18 = 324 , \text{in}^2$$

Step 2: Calculate the area of one triangular face

Each triangular face has a base of 18 in and a height (slant height) of 16 in.
$$\text{Area of one face} = \frac{1}{2} \times 18 \times 16 = 144 , \text{in}^2$$

Step 3: Calculate total lateral surface area

There are 4 identical triangular faces.
$$\text{Lateral Surface Area} = 4 \times 144 = 576 , \text{in}^2$$

Step 4: Sum base area and lateral surface area

$$\text{Total Surface Area} = 324 + 576 = 900 , \text{in}^2$$

Answer:

900