An unfolded cuboid is shown below.
What is the surface area of the cuboid?
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An unfolded cuboid is shown below.
What is the surface area of the cuboid?
To calculate the surface area of the rectangular prism, we will need to identify its three faces (each face appears twice):
1*3
1*8
3*8
The formula for the surface area of a rectangular prism is the sum of all the areas of the faces, that is:
We replace the data in the formula:
2*(1*3+1*8+3*8)=
2*(3+8+24) =
2*35 =
70
And this is the solution!
70
A cuboid is shown below:
What is the surface area of the cuboid?
Because every rectangular prism has 6 faces, but only 3 different sizes! Each face appears twice - on opposite sides. So you calculate the area of each unique face once, then multiply by 2.
Look at the three measurements of your cuboid (8, 3, 1). The three faces are formed by pairing these: 8×3, 8×1, and 3×1. Each pair creates one type of rectangular face.
The net shows all 6 faces unfolded! Count them carefully - you should see exactly 6 rectangles. The dimensions on the edges tell you the length and width of each face.
Yes! That's actually another correct method. Count all 6 rectangles in the net, find each area, then add them up. You'll get the same answer: 70 square units.
Check that you're calculating area (square units), not perimeter or volume. Make sure you've found all three face types and doubled each one. Common wrong answers like 35 come from forgetting to double.
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