Answer:
The answer to your problem is, 62.4 square centimeters
Explanation:
The picture of the question in the attached figure we know that
The surface area of the triangular pyramid is equal to the area of the triangular base plus the area of its three lateral triangular faces
In this problem the triangles are equilateral, that means, the surface area is equal to the area of four congruent equilateral triangles so:

now we can the following
bare = 6 centimeters
height = = 5.2 centimeters
We have to subistute

Thus the answer to your problem is, 62,4 centimeters