Answer:
156.6 square yards
Step-by-step explanation:
To find the surface area of the pyramid, find the area of each surface and add them together.
formula for area of a triangle = 1/2(b·h)
1. There are three triangles with a base of 9 and a height of 9
1/2(9·9) = 40.5
Multiply by the three triangles
40.5 · 3 = 121.5
2. There is one triangle with a base of 9 and a height of 7.8
1/2(9·7.8) = 35.1
3. Add the areas of all surfaces
121.5 + 35.1 = 156.6
