Scale Drawing Length and Area

Scale Drawing and Models

Lesson 7.5

Vocabulary

• A scale model/scale drawing is an object or drawing with lengths proportional to the object it represents.

• The scale of a model or drawing is the ratio of a length on the model or drawing to the actual length of the object being modeled or drawn.

Map Reading

• The scale on a map relates the size of an object on the map to its actual size.

  Where do you find the scale on a map/drawing?

• You have a scale drawing of a boat. The length of the boat on the drawing is 3 cm. What is the actual length of the boat?

Map Scales

• The map distance is about 1.6 cm from Charlotte to Winston-Salem.

• Use a proportion to find the actual distance. Let n represent the actual distance.

Map Scales

• The distance between Boston and Chicago on a map is 9 inches. If the scale of the map is 1 inch: 95 miles, what is the actual distance from Boston to Chicago?

• Write and solve a proportion. Let x represent the distance between Boston and Chicago.

Multiple Choice

The distance between Cheyenne, WY, and Tulsa, OK, on a map is 8 inches. If the scale of the map is 1 inch : 90 miles, what is the actual distance from Cheyenne to Tulsa?

• 800 miles

• 900 miles

• 630 miles

• 720 miles

Finding a Scale

• Refer to the model boxcar shown. The actual length of a boxcar is 609 in. What is the scale of the model?

Finding a Scale

• A miniature replica of a fighter jet is 4 inches long. The actual length of the jet is 12.8 yards. What is the scale of the model?

• To find the scale, write the ratio of a replica length to an actual length.

Multiple Choice

A miniature replica of a fire engine is 9 inches long. The actual length of the fire engine is 13.5 yards. What is the scale of the replica?

• 1 in. : 1.5 yd

• 1 in. : 3 yd

• 2 in. : 5 yd

• 3 in. : 4 yd

Using Scale Factors

• The scale factor of a drawing or scale model is written as a unit-less ratio in simplest form. 

• Scale factors are always written so that the model length in the ratio comes first.

Finding a Scale Factor

• A scale model of the Sergeant Floyd Monument is 10 inches tall. The actual monument is 100 feet tall.

• What is the scale of the model?

• What is the scale factor?