Answer :

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.