Ratio and scale Factors

Solve problems using ratio and scale factors in similar figures (ACMMG221)

LO:To solve problems using ratio and scale factors.
Know:

  • That shapes can be enlarged or reduced by scale factors..
  • What transformation is.

Understand:

  • That shapes can be enlarged or reduced by scale factors and ratios..

Do:

  • I can solve problems using ratio and scale factors in similar figures..

Scale Factor

Scale Factor is a ratio used as a multiplier/dividend in scaling (make an object bigger or smaller).

It’s the ratio of any two corresponding lengths in two similar figures.

These two figures on the left are similar figures because they maintain the same ratios. 16 = 32, 25 = 50, 22 = 44. Each side of the larger triangle is double the size of the smaller triangle, therefore the scale factor is 2.

This rectangle was enlarged by a scale factor of 4, since the original sides of the rectangle were increased by 4 times.

Scale factors can sometimes be a ratio amount and it doesn’t necessarily need to be a whole number.

Scale Factor Videos

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