How do you find the scale factor?

Answer 1

A scale factor tells how much the lengths in one diagram must be multiplied by to get the same lengths in a second.

One diagram could be a map and the second the real world!

To calculate the scale factor, measure the corresponding lengths in the same units and then divide the length of the second diagram by the length of the first diagram; this will give you the scale factor to convert the first diagram into the second diagram.

For example, if you were to draw a map of you street, you may decide that 2 centimetres on the map will represent 1 metre in the real world.

The ratio here is 2 cm : 1 m.

However, 1 m = 100 cm which means that the ratio is 2 cm : 100 cm

which is a scale factor of 100 cm ÷ 2 cm = 50.

Another example: if you have two similar triangles and the corresponding sides measure as 5cm in the first triangle and 2 cm in the second, the scale factor is 2 cm ÷ 5 cm = 2/5 or 0.4