Scale Drawings Teacher Twins 2014 Warm Up X2

Scale Drawings Teacher. Twins© 2014

Warm Up X=2 X=30 X= 6 37. 5 minutes

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A scale drawing is a proportional two-dimensional drawing of an object. When would you use a scale drawing?

The scale gives the relationship between the measurements on the drawing and the measurements of the real object. Examples: 1 inch = 3 feet 1 cm = 30 miles

Example 1: A scale drawing of a garden has a flower bed that is 6. 5 inches in length. The scale that was used for the drawing is 1 inch = 4 feet. What is the length of the actual flower bed? The flower bed is 6. 5 inches The scale tells s on the drawing. you that every inch on the drawing is equal to 4 feet in real life. Since every inch is 4 ft in real life you can multiply 6 x 4 and get 24. The half inch is equal to 2 (half of 4 feet). Add the 2 to 24 and you get a length of 26 ft. You can also multiply 6. 5 x 4 to get 26 ft.

Example 1 continued: A scale drawing of a garden has a flower bed that is 6. 5 inches in length. The scale that was used for the drawing is 1 inch = 4 feet. What is the length of the actual flower bed? We are going to write a proportion using the scale of the drawing. s The actual length of the flower garden is 26 ft.

Example 1 B: A scale drawing of a garden uses a scale that is 1 inch = 4 feet. If the garden is 12 feet in length how long will it be on the scale drawing? The garden is 12 feet in length. For every 4 feet in real life you have one inch on the scale drawing. Twelve divided by 4 gives you the length on the drawing which s is 3 inches. You can also think of it this way: 12 feet can be divided into 3 groups of 4 feet. 4 ft. 4 ft. 1 in 12 feet 3 inches

Example 1 B continued: A scale drawing of a garden uses a scale that is 1 inch = 4 feet. If the garden is 12 feet in length how long will it be on the scale drawing? We are going to write a proportion using the scale of the drawing. s 1 in 4 feet = x inches 12 feet The length of the flower garden on the drawing is 3 in.

Example 2: Finding Scales Find the scale used on a scale drawing of a bedroom if the actual length is 13 meters and the length on the scale drawing is 2. 5 centimeters. To find the scale, look at the measurement of the scale drawing and the actual object and put them in your proportion. We will find what 1 cm is equal to in the drawing, so we put a 1 to represent the drawing. The scale used for the drawing is 1 cm = 5 m.

Practice

Practice 3). What is the scale on a map, if the distance in real life is 50 miles and the distance on the map is 2. 5 inches? 4). Marci has a scale drawing of her new bedroom. On the drawing the length of the bedroom is 2 cm. In real life her bedroom is going to be 7 meters in length. What is the scale of the drawing?

Closure Give an example of when you would use scale drawings or scales in real life.