 Scale Drawings & Scale Models

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Scale Drawings & Scale Models
Created by: Mrs. Dube

Vocabulary 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

Finding a Scale Factor 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 1/12 Race Car Model Length (in.) 132 11 Height (in.) 66 5.5

Using Scale Factor Set up a proportion using the scale factor to find the unknown length Cross multiply and then divide

Using Scale Factor 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/ or 4/w= 1/15 l = 81 cm w = 60 cm Dimensions of actual painting: 81cm x 60 cm

Measurement Application
Using scale factor to find distance Set up proportion using scale factor and cross multiply and then divide to find missing distance

Scale Factor and 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 = Divide both sides by 3 d = 448 km

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