1. Scale Drawings

2. Scale – The ratio that compares the measurements of the real object and its model. EX: 1 in = 6 ft
Scale factor – written as a ratio without measurements and in simplest form EX: the scale factor of 1 in = 6 ft is 1/72

3. EX1) EX2) Identify the scale factor. Actual Model Length (in.) 12 2
Wing span (in.) 18 3
EX1)
model length
actual length 2 12 =
Write a ratio using one of the dimensions. 1 6 =
Simplify.
EX2)
The scale is 1 inch = 3 feet. What is the scale factor?
To eliminate units convert 3 feet to inches. Conversion factor is 1 foot = 12 inches
1 inch
3 feet
1 inch
36 inches = 1 36 =

4. EX3) = = Find the Scale Factor from the following shape small large
original
Model
original
small
Model
large 3 3 12 12 3
Model = 12
Model = 12
Original 3
Original 1 4
Scale factor =
Scale factor = 4 1

5. EX4)
A photograph was enlarged and made into a poster. The poster is 20.5 inches by 36 inches.
The scale factor is 5 . Find the size of the photograph. 1.
Draw a picture. 2.
poster
20.5
Write a proportion to find the length l and width w.
photo w l 36 3.
Solve the proportion.
poster
photo 5 1 36 l
poster
photo 5 1
20.5 w
Think: = = = =
36 X 1= 36
20.5 X 1= 20.5
36 ÷ 5 = 7.2
20.5 ÷ 5 = 4.1

8. Notes start here

9. assignment
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Problems 1-6

10. Date _______
Scaling Drawings

11. Scale – The ratio that compares the _________________ of the _____ object and its _______. EX: 1 in = 6 ft
Scale _______ – written as a ratio _______ measurements and in ________________ EX: the scale factor of 1 in = 6 ft is _______

12. EX1) EX2) Identify the scale factor. Actual Model Length (in.)
Wing span (in.)
model length
actual length =
Write a ratio using one of the dimensions. =
Simplify.
EX2)
The scale is 1 inch = 3 feet. What is the scale factor?
To eliminate units convert 3 feet to inches. Conversion factor is __________________
1 inch
3 feet = =

13. EX3) = = Find the Scale Factor from the following shape small large
original
Model
original
small
Model
large 3 3 12 12
Model =
Model =
Original
Original
Scale factor =
Scale factor =

14. EX4)
A photograph was enlarged and made into a poster. The poster is 20.5 inches by 36 inches.
The scale factor is . Find the size of the photograph. 5 1 1. 2. 3.
poster
photo
Think: