Answer:
644 cm²
Step-by-step explanation:
Surface area of the composite figure = surface area of the large rectangular prism + surface area of the small rectangular prism - 2(area of the surface of the small rectangular prism that joins the larger prism)
✔️Surface area of the large rectangular prism = 2(LW + LH + WH)
L = 6 cm
W = 5 cm
H = 20 cm
Surface area = 2(6*5 + 6*20 + 5*20)
= 500 cm²
✔️Surface area of the small rectangular prism = 2(LW + LH + WH)
L = 6 cm
W = 4 cm
H = 12 cm
Surface area = 2(6*4 + 6*12 + 4*12)
= 288 cm²
✔️area of the surface of the small rectangular prism that joins the larger prism = L*W
L = 12 cm
W = 6 cm
Area = 12*6
= 72 cm²
✅Surface area of the composite figure = 500 + 288 - 2(72)
= 644 cm²
