This document contains notes from a math lesson on using scale drawings to determine actual lengths and areas. It includes examples of determining scale factors from drawings and using them to calculate actual dimensions and areas. Homework assigned includes problems from the lesson on scale drawings as well as a test on this module coming up on Friday. The document provides instruction, examples, and practice problems for using scale factors to solve real-world geometry problems involving scale drawings.

1. Module 7.1 Lessons 18­19.notebook
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Lesson 18
Aim: Computing Actual Lengths from a Scale Drawing
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Homework:
1.) Lesson 18 Problem Set #1, 4, 6, 7
2.) Lesson 19 Problem Set #4
3.) End of Module Exam Friday 10/2
Do Now
Exit Ticket from Lesson 17

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3. Module 7.1 Lessons 18­19.notebook
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Check HW Answers: Page S.71

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Example 1: Basketball at Recess?
Vincent proposes an idea to the student government to install a basketball hoop along with a court
marked with all the shooting lines and boundary lines at his school for students to use at recess. He
presents a plan to install a half court design as shown below. After checking with school
administration, he is told it will be approved if it will fit on the empty lot that measures 25 feet by
75 feet on the school property. Will the lot be big enough for the court he planned?
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6. Module 7.1 Lessons 18­19.notebook
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scale = SF(actual)

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The constant of proportionality, k = the scale factor
y = drawing length
x = actual length
In example 1: k = y = kx

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Find the actual length: Find the actual width:

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Example 2:
The diagram shown represents a garden. The scale is 1 cm for every 20 meters of actual length. Find
the actual length and width of the garden based upon the given drawing. Each square in the drawing
measures 1 cm by 1 cm.
What is the scale factor (the constant of proportionality)?
Find actual length: Find the actual width:
k =
S.79
y = kx

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Example 3:
A graphic designer is creating an advertisement for a tablet. She needs to englarge the picture
given here so that 0.25 inches on the scale picture will correspond to 1 inch on the actual
advertisement. What will be the length and width of the tablet on the advertisement?
Find the scale factor:
Find the actual length:
Find the actual width:
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11. Module 7.1 Lessons 18­19.notebook
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Use the diagrams below to find the scale factor and then find
the area of each figure.
Example 1:
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Use the diagrams below to find the scale factor and then find
the area of each figure.
Example 2:
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Use the diagrams below to find the scale factor and then find
the area of each figure.
Example 3:
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Does the actual area you found reflect the results we found from
Examples 1–3? Explain how you know.
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Closing:
• What does the scale factor tell us about the relationship between the actual picture and
the scale drawing?
• How does a scale drawing differ from other drawings?