Answer:
27 cm²
Step-by-step explanation:
The surface area is the area of the square plus the area of the 4 congruent triangles.
area of square = 3² = 9 cm²
area of 1 triangle = [tex]\frac{1}{2}[/tex] × 3 × 3 = 4.5 cm²
area of 4 triangles = 4 × 4.5 = 18 cm²
Total surface area = 9 + 18 = 27 cm²
