Answer: 276 cm²
Explanation:
To find the surface area of this right-triangular prism we will find the area of the three rectangular sides and the area of the two triangle sides.
Area of a rectangle:
A = LW
A = (12 cm)(6 cm)
A = 72 cm²
Multiplying by 2 for the 2 congruent rectangles:
72 cm² * 2 = 144 cm²
Area of the third rectangle:
➜ We will use the given missing length of 8.
A = LW
A = (12 cm)(8 cm)
A = 96 cm²
Area of 2 congruent triangles:
A = 2 (
)
A = bh
A = (6 cm)(6 cm)
A = 36 cm²
Lastly, we will add these measurements together.
144 cm² + 96 cm² + 36 cm² = 276 cm²