Respuesta :

Each of the triangles making up the sides and base have a base of 8 cm and a height of 6.9 cm. Then the area of the pyramid is that of 4 such triangles.
  A = 4×(1/2)×b×h
  A = 2×(8 cm)×(6.9 cm)
  A = 110.4 cm²

The surface area of the triangular pyramid is 110.4 cm².
What we must do is observe that the triangles have the same measurements.
 We have then that the surface area is:
 A = (4) * (1/2) * (b) * (h)
 Where,
 b: base of the triangle
 h: height of the triangle
 Substituting values:
 A = (4) * (1/2) * (8) * (6.9)
 A = 110.4 cm ^ 2
 Answer:
 
The surface area of the triangular pyramid is:
 
A = 110.4 cm ^ 2