The net shows an equilateral triangle with side length 24 cm.
The area of an equilateral triangle of side length s is ...
... A = (√3)/4·s²
Using the above side length, the area is
... A = (√3)/4·(24 cm)² = 144√3 cm² ≈ 249.4 cm²
Your best choice is the first one:
... A) 249.6 cm²
