Answer:
SA = 5645cm²
Explanation:
We have three pairs of congruent rectangles
9cm × 4m; 9cm × 5cm and 4m × 5cm
We know 1m = 100cm, therefore 4m = 400cm
The formula of an area of a rectangle l × w:
A = l · w
Substitute:
A₁ = 9cm · 4m = 9cm · 400cm = 3600cm²
A₂ = 9cm · 5cm = 45cm²
A₃ = 4m · 5cm = 400cm · 5cm = 2000cm²
Calculate the surface area:
SA = A₁ + A₂ + A₃
SA = 3600cm² + 45cm² + 2000cm² = 5645cm²