Look at the the cuboid below.
What is its surface area?
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Look at the the cuboid below.
What is its surface area?
First, we recall the formula for the surface area of a cuboid:
(width*length + height*width + height*length) *2
As in the cuboid the opposite faces are equal to each other, the given data is sufficient to arrive at a solution.
We replace the data in the formula:
(8*5+3*5+8*3) *2 =
(40+15+24) *2 =
79*2 =
158
158
A cuboid is shown below:
What is the surface area of the cuboid?
A cuboid has 6 faces total - but they come in 3 pairs of identical opposite faces. The front and back faces are identical, the left and right faces are identical, and the top and bottom faces are identical. So we calculate the area of one face from each pair, then multiply by 2!
Think of the three different face types:
Don't worry! As long as you use each dimension exactly twice in your calculations, you'll get the right answer. The formula automatically accounts for this.
Yes! You can visualize each face and calculate them individually:
Your surface area should be larger than any single face area. Here, our biggest face is 5×8=40, and 158>40 ✓. Also, it should be less than if we calculated all faces separately without sharing edges.
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