Length, area and volume factors

Length, area and volume factors

Secondary 3
TGM Original Questions

Choose the measure before the multiplier

Geometrically similar figures have the same shape. If every corresponding length is multiplied by a positive factor \(k\), every corresponding area is multiplied by \(k^2\), and every volume by \(k^3\). Perimeters follow the length factor.

The rectangles above have length factor 2, but their areas are \(2\text{ cm}^2\) and \(8\text{ cm}^2\): an area factor of 4. Doubling three perpendicular dimensions gives a volume factor of 8.

MeasureRatio, small : large
Corresponding length or perimeter\(a:b\)
Area or corresponding surface area\(a^2:b^2\)
Volume or capacity\(a^3:b^3\)

Write the direction of your ratio before substituting. Similar heights alone do not prove two arbitrary solids geometrically similar; all corresponding dimensions must have the same factor.

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