​Reduction

​This picture is an example of a reduction. Can you see why?

​Enlargement

​This picture is an example of an enlargement. Can you tell why?

​Scales and their meanings

​Scales are written as ratios comparing the drawing or image to the actual object.

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​ The scale for this enlargement is 25:100 which can be simplified to 1:4

​The scale for this reduction is 6: 1

​Scales and their meanings

​If you examine the numbers in the scale which is 36 : 12, you will realize that the image is 3 times larger than the object 12 x 3 = 36). That means that the object is one-third the size of the image. (36/3 = 12). That means that means that the scale can be simplified to 3 : 1.

​Scales and their meanings

​What does the scale of 1 : 100 on the diagram means? Well, it simple means that for every 1 cm you measure on the image or drawing, it represents 100 cm on the actual building.

​Scales and their meanings

​ A scale of 3 : 150 means that for every 3 units on the drawing, it represents 150 units on the actual object. Since 3 x 50 = 150, then the actual building is 50 times the size of the drawing. The scale 3 : 150 can be simplified to 1 : 50, which means that for every 1 unit on the drawing, it represents 50 units on the actual building.

​Simplifying the scale (Equivalent scales)

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​Equivalent Scales

1 : 50 is equivalent to 4 : 200 Can you think of any other scale that would be equivalent to 1: 50?

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​The scale on the drawing is 1 : 100. That means that every 1cm on the drawing represents 100cm on the actual building or that the building is 100 times the size of the drawing. 

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​The perimeter of the drawing is 70cm ( Do you see how we got 70? If you don't, be sure to ask Mrs. Hemmings to explain when you see her. Don't forget now)

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​If the drawing has a perimeter of 70m, then the actual building must have a perimeter that is 100 times longer. Therefore, the perimeter of the building is 7000cm (70 x 100). 

​REMEMBER THAT 100cm IS THE SAME AS 1m. SO 7000cm IS 70m

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An architect drew a scaled drawing of a school. The scale he used was 1cm∶5meters.The school is 5 centimeters wide in drawing. How wide is the school in real life?

​Since 1cm on the drawing represents 5m on the actual school. 5cm would represent 25m.

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​Question

In a plan of a residential compound, if the buildings are 5 cm in height, the plan uses a

1 cm : 3 m scale. What is the height of the buildings in real life?

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SOLUTION​

​Question

A map has a scale of 2cm : 6km. The actual distance between two cities is 72km. What is the distance between the cities on the map? 

SOLUTION​