Scale drawing – a proportional two-dimensional drawing of an object

Scale factor – the ratio used to enlarge or reduce similar figures

Scale model – a proportional three-dimensional model of an object

Scale – the ratio between two sets of objects

Create a ratio comparing the figures Next, simplify the ratio Ex. Use either lengths or heights to

create the ratio to find the scale factor : 11/132 or 5.5/66

Simplify: ÷ by 11: 1/12 or 1/12Race Car

Model

Length (in.) 132 11

Height (in.) 66 5.5

Set up a proportion using the scale factor to find the unknown length

Cross multiply and then divide

A photograph has dimensions 5.4 cm and 4 cm. The scale factor is 1/15. Find the size of the actual painting: photo/painting = 1/15› 5.4/l = 1/15 or 4/w= 1/15 l = 81 cm w = 60 cm Dimensions of actual painting: 81cm x 60 cm

Using scale factor to find distance Set up proportion using scale factor

and cross multiply and then divide to find missing distance

The distance on a map between two cities is 10.5cm. The map scale is 3 cm = 128 km.3/128 = 10.5/d

3d = 1344 Divide both sides by 3 d = 448 km