If you like model airplanes, you probably already know all about scale factor. If we have a kit to build a Jetstream 200, for example, this means that we're building a model plane that is exactly the size of a real Jetstream 200 across all 3 dimensions. The same general concept can be applied to geometric figures.
If we have two similar figures of different sizes, their scale factor tells us the ratio of one size to the other. For example, we might have these two triangles:
As we can see, these two triangles are similar. We can also see that the larger triangle has a side that is four times the size of the corresponding side of the smaller triangle. we can solve for the scale factor by finding the ratio of two corresponding sides.
Because these two triangles are similar, this means that the scale factor is "4."
Which then tells us the remaining two unknown sides of the larger triangle
When we dilate an object, we enlarge it. We do this by changing the area with a scale factor of .
If we were working with a three-dimensional object (such as a model airplane), the scale factor would be .
We can use scale factor to help with a number of real-world problems:
Common Core: High School - Geometry Flashcards
Common Core: High School - Geometry Diagnostic Tests
Intermediate Geometry Diagnostic Tests
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