1 Chapter 6 Lesson 3 Scale Drawings & Models pgs. 276-280 What you will learn:Use scale drawingsConstruct scale drawings
2 VocabularyScale drawing/scale model (276): is used to represent an object that is too large or too small to be drawn or built at actual sizesScale (276): gives the relationship between the measurements on the drawing or model and the measurements of the real objectScale factor (277): the ratio of a length on a scale drawing or model to the corresponding length on the real object
3 Scale Example: 1 inch = 3 feet (One inch represents an actual distance of 3 feet)1:24(1 unit represents an actual distance of 24 units)
4 Scale FactorExample: Suppose a scale model has a scale of 2 inches = 16 inches. The scale factor is 2 or8The lengths and widths of objects of a scale drawing or model are proportional to the lengths and widths of the actual object.
5 Example 1: Find Actual Measurements A set of landscape plans shows a flower bed that is 6.5 inches wide. The scale on the plans is 1 inch = 4 feet.What is the width of the actual flower bed?Let x represent the actual width of the flower bed. Write and solve a proportion.Plan width----> 1 inch = 6.5 inches<---plan widthActual width--> 4 feet x feet <-----actual width1x = 4 cross productsx= 26 The actual flower bed width is feet.
6 From the last example, what is the scale factor? To find the scale factor, write the ratio of 1 inch to 4 feet in simplest form.1inch = 1 inch Convert 4 feet4 feet inches to inchesThe scale factor is That is , eachmeasurement on the plan is 1 the actual measurement
7 Example 2: Determine the Scale In a scale model of a roller coaster, the highest hill has a height of 6 inches. If the actual height of the hill is 210 feet, what is the scale of the model?Model height---> 6 inches = 1 inch <--model heightActual height--->210 feet x feet <--actual height6x = 2106x = x= 35So, the scale is 1” =35 feet
8 Example 3: Construct a Scale Drawing A garden is 8 feet wide by 16 feet long. Make a scale drawing of the garden that has a scale of 1 in. = 2ft.4Step 1: Find the measure of the garden’s length on the drawing. Let x represent the length.drawing length--> .25in = x in <--drawing lengthactual length--> ft ft <---actual length.2516 =2x4 = 2x2 = xOn the drawing, the length is 2 inches
9 drawing width--> .25 in = w inches <--drawing width Step 2: Find the measure of the garden’s width on the drawing. Let w represent the width.drawing width--> .25 in = w inches <--drawing widthactual width ---> 2 feet feet <---actual width.258 = 2w2 = 2w1 = wOn the drawing the width is 1 inch.
10 8 ft Step 3: Make the scale drawing. Use 1/4” grid paper. Since 2” = 8 squares and 1 inch = 4 squares, draw a rectangle that is 8 squares by 4 squares.< ft >8 ft
11 Your Turn!On a set of architectural drawings for an office building, the scale is 1/2” = 3 feet. Find the actual length of each room.Lobby: 2 inchesCafeteria: 8.25 inches.5” = 2”3ft x ft.5x = The actual lengthx = of the lobby is 12 ft.5” = 8,25”3ft x ft The actual length of the.5x = cafeteria is 49.5 feetx = 49.5
12 Your Turn, Again!In an illustration of a honey bee, the length of the bee is 4.8 cm. The actual size of the honeybee is 1.2 cm. What is the scale of the drawing?4.8 cm = 1cm1.2 cm x cm4.8x = 1.2x = .25The scale of the drawing is 1 cm = .25cm
13 Extra Practice sheets are by the door on your way out, be sure to grab one! Quiz over 6-1 thru 6-3 Tomorrow!