To find the surface area of a rectangular prism, you can use the formula:
\[ \text{Surface Area} = 2(lw + lh + wh) \]
where:
- \( l \) is the length,
- \( w \) is the width,
- \( h \) is the height.
Given:
- Length \( l = 12 \) inches
- Width \( w = 8 \) inches
- Height \( h = 3 \) inches
Now, we can calculate the surface area step by step.
-
Calculate the area of each pair of opposite faces:
- Area of the length and width faces: \( lw = 12 \times 8 = 96 \) square inches
- Area of the length and height faces: \( lh = 12 \times 3 = 36 \) square inches
- Area of the width and height faces: \( wh = 8 \times 3 = 24 \) square inches
-
Now, sum these areas: \[ lw + lh + wh = 96 + 36 + 24 = 156 \]
-
Finally, multiply by 2 to find the total surface area: \[ \text{Surface Area} = 2 \times 156 = 312 \text{ square inches} \]
Therefore, the surface area of the gift box is 312 square inches.