What is it?????

What is SCALE FACTOR?

• ​A scale factor in math is the ratio between corresponding measurements of an object and a representation of that object. It is most commonly written with a colon :

Scale factors are proportional. So you need to set up a proportion to solve!

Remember - proportions are just equivalent ratios.

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​TYPES OF SCALE DRAWINGS

• If the scale drawing is LARGER than the original, then it is an enlargement. The scale factor is GREATER than 1.

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• If the scale drawing is SMALLER than the original, then it is a reduction. The scale factor is LESS than 1.

Example:

​Remember to cross multiply then divide to solve for x!

Finding the Scale Factor

Finding the Scale Factor

In order to use a scale factor, multiply each side length by the scale factor to find the new side length for the scaled copy.

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If the scale factor is 3, then each side will be exactly ​three times as big as in the original image.​ (This means the longest side in your SCALED COPY in this case will be 27 in.)

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Using the Scale Factor

Using the Scale Factor

​A photo is being resized.  The original photo is 4 inches by 6 inches.  Given the dimensions of the resized photo, find the scale factor.

1. 2.5 in. by 3.75 in.

​A photo is being resized.  The original photo is 4 inches by 6 inches.  Given the dimensions of the resized photo, find the scale factor.

1. 12 in. by 18 in.

How do we find the scale ratio?

• write the ratio of the model to the actual size

• simplify!

Example:

How to solve?

• Second number

• divide by

• first number