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Example 4-4b Objective Solve problems involving scale drawings

Example 4-4b Vocabulary Scale drawing Something that is too large or too small to be drawn at actual size

Example 4-4b Vocabulary Scale Gives the relationship between the distance on the map and the actual distance

Example 4-4b Vocabulary Scale factor A scale written as a ratio in simplest form

Example 4-4b Vocabulary Scale model Used to represent something that is too large or too small for an actual-sized model

Lesson 4 Contents Example 1Use a Scale Drawing Example 2Read a Scale Drawing Example 3Find the Scale Factor Example 4Make a Scale Model

Example 4-1a MAPS On the map below, the distance between Portland and Olympia is about inches. What is the actual distance? 1/4 Use the scale to write a ratio map → actual → Write the second ratio with information given

Example 4-1a MAPS On the map below, the distance between Portland and Olympia is about inches. What is the actual distance? 1/4 map → actual → Define the variable Let d represent actual distance

Example 4-1a Cross multiply Multiply. 46 Ask “what is being done to the variable”? Do the inverse on both sides of the equal sign 7 8 1/4

Example 4-1a Combine “like” terms 46 Answer: miles 7 8 1/4 Add dimensional analysis

Example 4-1b Answer: d = 750 miles MAPS On a map, the scale is given as 2 inches 100 miles. If the distance on the map between two cities is 15 inches, what is the actual distance between the two cities? 1/4

Example 4-2a ARCHITECTURE On the blueprint of a new house, one- quarter inch represents feet. If the length of a bedroom on the blueprint is inches, what is the actual length of the room? Write scale in ratio form blueprint → actual → 2/4

Example 4-2a ARCHITECTURE On the blueprint of a new house, one- quarter inch represents feet. If the length of a bedroom on the blueprint is inches, what is the actual length of the room? Write the other ratio with what is known blueprint → actual → 2/4

Example 4-2a ARCHITECTURE On the blueprint of a new house, one- quarter inch represents feet. If the length of a bedroom on the blueprint is inches, what is the actual length of the room? Define variable Let l = actual length blueprint → actual → 2/4

Example 4-2a Cross multiply 2/4 Multiply = Ask “what is being done to the variable”? Do the inverse on both sides of the equal sign Combine “like” terms feetAnswer: Add dimensional analysis

Example 4-2b ARCHITECTURE On a blueprint of a new house, one- quarter inch represents 3 feet. If the width of the kitchen on the blueprint is 2 inches, what is the actual width of the room? Answer: w = 24 feet 2/4

Example 4-3a Find the scale factor of a blueprint if the scale is Write the ratio of in simplest form. Convert 3 feet to inches. 3/4

Example 4-3a Find the scale factor of a blueprint if the scale is Cancel the units. 3/4 Multiply the numerator and denominator by 2 to eliminate the denominator  2 inch inches Answer:

Example 4-3b Find the scale factor of a blueprint if the scale is 1 inch 4 feet. Answer: 3/4

Example 4-4a PHOTOGRAPHY A model is being created from a picture frame which has a length of inches. If the scale to be used is 8 inches 1 inch, what is the length of the model? 4/4 Write scale in ratio form Write second ratio with information given Define variable Let m = length of model

Example 4-4a 4/4 Cross multiply Multiply Add dimensional analysis Answer: m = 38 inches

Example 4-4b FURNITURE A model is being created from a child- sized rocking chair which has a height of 8 inches. If the scale to be used is 12 inches 1 inch, what is the height of the model? Answer: h = 96 inches * 4/4

End of Lesson 4 Assignment Lesson 7:4Geometry: Scale Drawing All