Scale Drawings Scale Factor Ratio A ratio is

Scale Drawings & Scale Factor

Ratio • A ratio is a comparison of two quantities

Scale • A scale is a ratio between two sets of measurements. – Examples: • Drawings: ¼ inch = 1 foot • Maps: 1 inch = 250 miles

Scale Drawing (Model) • A scale drawing (model) is a drawing that uses a scale to make an object smaller than (reduction) or larger than (enlargement) the real object.

Scale Factor • A scale factor is a ratio used to enlarge or reduce similar figures. – Examples: enlarging a piece of candy for a drawing…or the Willy Wonka Factory…

The lengths and widths of objects of a scale drawing or model are proportional to the lengths and widths of the actual object.

Practice Problems

1. 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. a. What is the width of the actual flower bed? 26 feet b. What is the scale factor? 1/48

2. The central chamber of the Lincoln memorial, which features a marble statue of Abraham Lincoln, has a height of 60 feet. Suppose a scale model of the chamber has a height of 4 inches. What is the scale of the model? a. Write a ratio of the height of the model to the actual height of the statue? 60 ft 15 ft 4 in 1 inch = 15 feet b. What is the scale factor? 1/180

3. Antonio is designing a room that is 20 feet long and 12 feet wide. Make a scale drawing of the room. Use the scale 0. 25 inches = 4 feet. STEP 1: Find the room’s length on the drawing (let x = length) 20 x = 4 Length = 1. 25 inches . 25 STEP 2: Find the room’s width on the drawing (let w = width) 12 x = 4 . 25 Width =. 75 inches

STEP 3: Make a drawing. Assume the grid below is ¼ inch grid paper.