Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
4. Surface Areas and Volumes of Similar Solids
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Exercise 3 Page 447

When two solids are similar, the ratio of their surface areas is equal to the ratio of their corresponding linear measures squared.

237.5 square meters

Practice makes perfect

We know the side of two similar rectangular prisms but the surface area of just one of them.

We will use the fact that these prisms are similar to find the suface area of the smaller solid. When two solids are similar, the ratio of their surface areas is equal to the ratio of their corresponding linear measures squared. Surface area of the smaller solid/Surface area of the bigger solid = (Side of the smaller solid/Side of the bigger solid)^2 We know that the side and the surface area of the bigger solid are 8 meters and 608 square meters, respectively. We also know that the side of the smaller solid is 5 meters. If we let S be the surface area of the smaller solid, we can substitute these values into the equation and solve for S.

Surface area of the smaller solid/Surface area of the bigger solid=(Side of the smaller solid/Side of the bigger solid)^2
S/608=(5/8)^2
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Solve for S
S/608=5^2/8^2
S/608=25/64
S=25/64 * 608
S=25 * 608/64
S=15 200/64
S=237.5

The surface area of the smaller rectangular prism is 237.5 square meters.