Answer:
144
Step-by-step explanation:
4 triangles = 1/2 x 6 x 9 x 4 = 108
1 sq base = 6 x 6 = 36
total surface area = 36 + 108 = 144
if 3 triangles the base wouldn't be a square thus not possible to solve
SA = Area of base + 4 area of triangles
6² + 4(9 × 6 × 1/2)
36 + 4(27)
= 144
