Question

Find the surface area of the pyramid.

Answer 1

Answer:

A. 311.4 ft²

Step-by-step explanation:

Use the formula for the surface area of a square pyramid: SA = 2bs + b², where b is the length of a side of the base and s is the slant height.

Plug in the values and solve:

SA = 2(9)(12.8) + 9²

SA = 230.4 + 81

SA = 311.4 ft²

Answer 2

Answer:

A. 311.4

Step-by-step explanation:

The surface area of a 3D figure is simply the sum of the areas of all the exterior surfaces.

Here, the pyramid has a square base with dimensions 9 ft by 9 ft, as well as four lateral isosceles triangles.

The area of a square is denoted by A = s², where s is the side length. Here, the side length is 9, so:

A = s²

A = 9² = 81 ft²

We know that the height of the triangle is 12.8 and the base is 9. Use the area formula of a triangle, which is A = (1/2) * bh, where b is the base and h is the height:

A = (1/2) * bh

A = (1/2) * 9 * 12.8 = 57.6 ft²

Since there are four of these triangles, multiply 57.6 by 4:

57.6 * 4 = 230.4 ft²

Finally, add 230.4 to 81:

81 + 230.4 = 311.4 ft²

The answer is thus A.

~ an aesthetics lover