Transcript 6-3: Scale Drawings

Problem of the Day
1) Find the Length of the missing side.
5-8: Scale Drawings and Scale Models
Making comparisons and finding dimensions
of scale drawings, models, and actual objects
Vocabulary
Scale Drawing
A two dimensional drawing that is used to represent an
object that is too large or small to be drawn at actual size
(blue prints, maps, assembly instructions, etc.).
Scale Model
A three dimensional object that is used to represent an
object that is too large or small to be drawn at actual size
(model cars, model buildings).
Vocabulary
Scale
The ratio of the dimensions in a drawing to the dimensions
of the actual object.
Vocabulary
Scale
The ratio of the dimensions in a drawing to the dimensions
of the actual object.
Ex: The scale on map may be 1 in: 10 miles, 1 in to 10
miles, or 1inch
10 miles
Vocabulary
Scale Factor
The ratio of a length on a scale drawing or model to the
corresponding length on the real object is called the
scale factor
Vocabulary
Scale Factor
The ratio of a length on a scale drawing or model to the
corresponding length on the real object is called the
scale factor.
Example
Scale model has a scale of 2 inches = 4 feet. To find the
scale factor, set up a ratio and convert to same units….
Vocabulary
Scale Factor
The ratio of a length on a scale drawing or model to the
corresponding length on the real object is called the
scale factor.
Example
Scale model has a scale of 2 inches = 4 feet. To find the
scale factor, set up a ratio and convert to same units….
2in
2in
1in


4 feet 48in 24in
Vocabulary
Scale Factor
The ratio of a length on a scale drawing or model to the
corresponding length on the real object is called the
scale factor.
Example
Scale model has a scale of 2 inches = 4 feet. To find the
scale factor, set up a ratio and convert to same units….
2in
2in
1in


4 feet 48in 24in
1
1
The scale factor is
… The drawing is
the size of
24
24
the actual object
Vocabulary
A scale drawing or model that is smaller than the actual
object is called a Reduction. A scale drawing or model
that is larger than the object is called an Enlargement.
Steps in Solving
To find the missing length of an actual object using a
given scale…
I. Write a proportion using the given scale; setting it equal
to the given actual size and the missing measurement.
II. Be sure to place corresponding units across from each
other.
Examples
A model of a 27 ft. tall
house was made using a
scale of 2 in: 3 ft. What is
the height of the model?
Under a 1,000:1 microscope
view, an amoeba appears to
have a length of 8 mm.
What is its actual length?
Problems/Examples of
A) The length of an object
on a scale drawing is 2
cm, and its actual length
is 8 m. The scale is 1
cm: _______ m. What is
the scale?
B) What is the scale of a
drawing in which a 9 ft.
wall is 6 cm long?
Problems/Examples of
Find the Scale Factors
C) 1 in.: 4 ft.
D)
2 ft.: 6 in.
E)
2 ft.: 30 yd
Problems/Examples of
F) Using a 1 in. = 1 ft.
4
scale, how long would a
drawing of a 22 ft. car be?
G) The height of a person
on a scale drawing is 4.5 in.
The scale is 1:16. What is
the actual height of the
person?
Problems/Examples of
Tell whether each scale reduces,
enlarges, or preserves the size of
an actual object.
J.
50 ft.: 1 in.
K.
0.2 in: 2 ft
H. 10 ft. : 24 in.
I.
1 mi: 5,280 ft.
Now try these…
1) A map has a scale of 1 inch = 8 miles.
two towns are 3.25 inches apart on the
map.
What is the actual distance between the
two towns?
Now Try These…
1) A map has a scale of 1 inch = 8 miles. Two
towns are 3.25 inches apart on the map.
What is the actual distance between the two
towns?
1inch
3.25inches

8miles
Xmiles
x = (3.25)(8 miles)
x = 26 miles
Now Try These…
2)
A map has a scale of 1 inch = 8 miles.
two towns are 3.25 inches apart on the
map.
What is the scale factor?
Now Try These…
2)
A map has a scale of 1 inch = 8 miles.
two towns are 3.25 inches apart on the
map.
What is the scale factor?
3.25inches
26 miles
Now Try These…
2)
A map has a scale of 1 inch = 8 miles.
two towns are 3.25 inches apart on the
map.
What is the scale factor?
3.25inches
3.25inches
1inch


26m iles
1,647,360inches 506,880inches
Now Try These…
3)
A model car is 4 inches long. The
actual car is 12 feet long. What is the
scale of the model?
Now Try These…
3)
A model car is 4 inches long. The
actual car is 12 feet long. What is the
scale of the model?
4inch 1inch

12 feet xfeet
Now Try These…
3) A model car is 4 inches long. The actual car is
12 feet long. What is the scale of the model?
4inch 1inch

12 feet xfeet
4x =12
x=3
Now Try These…
3) A model car is 4 inches long. The actual car is 12 feet
long. What is the scale of the model?
4inch 1inch

12 feet xfeet
4x =12
x=3
1inch
3 feet
or 1 inch = 3 feet