Question

Lucas built a composite solid by joining 12 identical blocks, with dimensions 4 inches by 5 inches by 7 inches, into three

Answer 1

Answer:

1042 square inches is the total surface area of composite solid.

Step-by-step explanation:

It is clear from the image that the resulting composite solid is a cuboid.

whose sides are as follows:

Across the length there are 3 blocks along the side of 7 inches each.

Length = $7 \times 3 = 21\ inch$

Width = 5 inch

Across the height there are 4 blocks along the side of 4 inches each.

Height = $4 \times 4 = 16\ inch$

We know that total surface area of a cuboid is as follows:

$\text{Total Surface Area = } 2 (l\times w+ w \times h+ h \times l)$

$\Rightarrow 2 (21 \times 5 + 16 \times 21 + 16 \times 5 )\\\Rightarrow 2 (105 + 336+80)\\\Rightarrow 2 \times 521\\\Rightarrow 1024$

Hence, total surface area = 1024 square inches