Answer:
21.8 + (3/2)(7.1)(13)
Explanation:
The surface area (SA) is the sum of the base area (B) and lateral area (LA). The lateral area is the sum of the areas of the three face triangles.
SA = B + LA
LA = 3((1/2)bh)) . . . . b is the base length of the triangle, and h is its height
Using appropriate substitutions, we have ...
SA = 21.8 + (3/2)(7.1)(13)