Answer: 324 cm²
Step-by-step explanation:
To find the surface area of this prism, we can break it up into two different rectangular prisms. Then, the surface area of a rectangular prism can be found with SA = 2lw + 2wh + 2lh.
We will have a 3 cm x 9 cm x 4 cm and a 3 cm x 3 cm x 9 cm prism. See the attached image for a visual of how I broke it up.
SA = [2lw + 2wh + 2lh] + [2lw + 2wh + 2lh]
SA = [2(6 cm)(3 cm) + 2(3 cm)(9 cm) + 2(6 cm)(9 cm)] + [2(3 cm)(3 cm) + 2(3 cm)(9 cm) + 2(3 cm)(9 cm)]
SA = [36 cm² + 54 cm² + 108 cm²] + [18 cm² + 54 cm² + 54 cm²]
SA = [198 cm²] + [126 cm²]
SA = 324 cm²
