Answer:
261 cm²
Step-by-step explanation:
To find the surface area of a square pyramid, you must first recognize all of the shapes.
There are four triangles and one square.
- To find the area of a square, multiply the side by itself twice.
- To find the area of a triangle, multiply the base and the height, then multiply the product by 1/2.
The triangles have a base of 9 and a height of 10.

Multiply the product by 1/2.

There are four triangles.

The area of all three triangles is 180 centimeters; the area of a single triangle is 45 centimeters.
There square has sides of 9 centimeters.

The area of the square is 81 centimeters.
Lastly, we add the areas of the shapes.

Therefore, the surface area of this square prism is 261 cm².
You can use this layout to find the surface area of a square pyramid.