Scale drawings and maps

•A

scale is the ratio between 2 corresponding measurements

•A

scale drawing is a drawing that uses a scale to represent an object as being smaller or larger than the actual object

Scale drawing • The second rectangle is a scale drawing

of the first rectangle with a scale of

• 1 cm. : 5 in. ( every cm. on the scale

drawing represents 5 in. of the actual figure.

10 in.

4 in.

2 cm.

.8 cm.

Making a scale drawing • The White House is approximately 168

ft. long and 85 ft. wide. Draw a scale representation of the base of the building using a scale of 1 cm: 30 ft.

• Give your answer to the nearest tenth. • 1) set up a proportion with scale on 1

side and length, width, w l of the White House on the other side- then do the same with

•

l = 1cm. w = 1 cm.

• 168 ft. 30 ft. 85 ft. 30 ft.

Making a scale drawing • The actual hind leg of a

grasshopper is 1.5 inches long and its antennae are .25 inches long. If a scale drawing for the grasshopper is 1 in. to 4 cm., what are the lengths in the drawing?

• 1 in. = 1.5 in.

1 in. = .25 in.

• 4 cm. Leg 4 cm. anten

• Scale drawings

are often used when the object is either too large or too small to be represented on paper.

• A

scale model is a 3-dimensional model that uses scale to represent an object smaller or larger than the actual object.

Making a scale model.

• The carbon atom, which is roughly

spherical, has an atomic radius of 70 picometers. If a student models the carbon atom with a scale of 5pm: 1 cm., what is the radius of the model?

• 1 cm. = x • 5 pm. 70 pm.

Maps • Adina lives 145 meters from

Darren. On the map, that distance is represented as 2 cm. If, on the map, Carmen lives 3.5 cm. from Darren and 4 cm. from Adina, what is the actual distance that Carmen lives from Adina and Darren?

practice • 1. Make a scale drawing of the base of an

apartment building that is 30 meters long and 15 meters wide. Use a scale factor of 1 m: .5 cm.

• 2. The Washington Monument is approximately

555.5 feet tall. If a scale drawing is 10 inches tall, what is the scale?

• 3. The planet Mercury has a diameter of 3031

miles. If a scale model is made with a ratio of 200 miles to 1 foot, what is the diameter of the model, to the nearest tenth?

• 4. On a map of the U.S., San Antonio is 3.3 cm.

away from Dallas. They are actually 277 miles apart. If Oklahoma City is 2.4 cm. away from Dallas on the same map, how far apart the 2 cities, to the nearest whole number?