Answer:
(a) 116.8 in²
Step-by-step explanation:
You want the surface area of the rectangular pyramid with side lengths 6 inches and 5 inches, and slant heights from those edges of 7.8 inches and 8 inches.
Base
The area of the base is ...
A = LW
A = (6 in)(5 in) = 30 in²
Faces
The area of the two triangular faces with base 6 inches is ...
A = 2×1/2bh = (6 in)(7.8 in) = 46.8 in²
The area of the two triangular faces with base 5 inches is ...
A = bh = (5 in)(8 in) = 40 in²
The total surface area is the sum of the base and face areas:
30 in² +46.8 in² +40 in² = 116.8 in²
The surface area of the pyramid is 116.8 square inches, choice A.
