Scale Factor and the Relation of Scale Factor to Area

This is a line.  

If this line is multiplied by a scale factor of 2, it gets bigger    (2cm x 2 = 4cm)

If this same line     is multiplied by a scale factor of 0.5 (½), it gets smaller    (2cm x 0.5 = 1cm)

Therefore, a scale factor is a number that is multiplied by the length of a line to get the length of a second, similar line.  Scale Factor 

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Practice using scale factor to find the second length. To use scale factor to calculate a new dimension, the measurements must be in the same units. 

Practice with these. Use pencil and paper, a calculator or the tool below:

These are harder:

Enter the original length:   Multiply by the scale factor:

Want to try some more?  

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Practice calculating the scale factor. To find the scale factor the measurements must be in the same units. Divide the second measure by the first or original measure,

Enter the first length:   Enter the second length: Divide the second length by the first:

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Scale factor is usually used when checking to see if figures are similar. There are two things needed for figures to be similar: Corresponding angles must be congruent. The ratio of corresponding sides must be the same.

Use the tools above to check these calculations.

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