If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

# Identifying scale copies

Sal looks at side measures on figures to determine if they are scale copies.

## Want to join the conversation?

• how can we actually calculate the scale copy of one figure to the other figure?
Any answers or comments will be helpful.
Thanks to people who help to answer this question.
#patient for answer#
(15 votes)
• Eunice, first you have to look at one of the sides of the scaled copy. If they are divisible by the numbers in the original shape, then try and see if the others sides of the scaled copy are scaled by the same factor. If they are, then they are a scaled copy. Hope this helped!
(25 votes)
• on your practice can you make the lines for the squares more visable, it is kind of hard to see.
(7 votes)
• I don’t think he can do that. He would have to change the code for the exercises which he cannot do
(3 votes)
• Guys im in 3rd grade lol
(7 votes)
• Get better :)
(3 votes)
• How would we do this with 3D shapes instead of 2D?
(8 votes)
• this to easy
(7 votes)
• Maybe for you its easy.
(2 votes)
• what is a scale copy? Help me plz.
(0 votes)
• A scale copy of a figure is a figure that is geometrically similar to the original figure.

This means that the scale copy and the original figure have the same shape but possibly different sizes.

More precisely, the angles of the scale copy are equal to the corresponding angles of the original figure, and the ratio of the side lengths of the scale copy is the same as the ratio of the corresponding side lengths of the original figure.

In real life, a scale copy is often smaller than the original figure. For example, the drawing of a floor plan for a room is a scale copy of the actual floor of the room. The floor plan drawing has the same shape as but is smaller than the actual floor. For example, if the actual floor is a rectangle measuring 12 feet by 16 feet, a scale copy could be a drawing of a 6-inch by 8-inch rectangle (because 12ft:16ft is the same ratio as 6in:8in).
(14 votes)
• those rocks on the quizes be giving me the light skin stare.
(5 votes)
• why dont you count the top thats the key to finding the answer.
(3 votes)
• why do we mesure sides of the scale copies
(3 votes)
• how do we find out the volume of x
(3 votes)

## Video transcript

- [Instructor] What we're going to do in this video is look at pairs of figures, and see if they are scaled copies of each other. For example, in this diagram, is Figure B a scaled version of Figure A? Pause the video and see if you can figure that out. There's multiple ways that you could approach this. One way is to say, "Well, let's see what the scaling factor would be." We could look at the side lengths. This side right over here has length three on Figure A. This side length right over here has length one, two, three, four, five. This side length has length five as well. This has length five. This length, we could figure it out with the Pythagorean Theorem, but I won't even look at that one just yet. But let's look at corresponding sides. To go from this side. If we scale up, the corresponding side to that would be this side right over here. What is its length? Well, its length, when you scale it up, looks like five. So to go from three to five you would have to multiply by 5/3. 5/3. But let's look at this side now. It's five in Figure A. What length is it in Figure B? Well, it is one, two, three, four, five. It's still five, so to go from five to five, you have to multiply it by one, and so you have a different scaling factor for corresponding, or what could have been corresponding sides. This side right over here, you're scaling up by 5/3, while this bottom side, this base right here, you're not scaling at all. So these actually are not scaled versions of each other. Let's do another example. In this example, is Figure B a scaled version of Figure A? Pause the video and see if you can figure it out. All right, well we're gonna do the same exercise, and here they've given us the measures of the different sides. This side has length two. This side has length the corresponding side, or what could be the corresponding side has length six. To go from two to six, you have to multiply by three. If we look at these two potentially corresponding sides, that side and that side, once again, to go from four to twelve, you would multiply by three, so that is looking good as well. Now to go from this side down here, this has length six. The potentially corresponding side right over here has the length 14. Well here we're not multiplying by three. If these were scaled If Figure B was a scaled-up version of Figure A, we would multiply by three, but six times three is not 14, it's 18, so these actually are not Figure B is not a scaled version of Figure A. Let's do one more example. Once again, pause this video and see if Figure B is a scaled version of Figure A. We're gonna do the same exercise. Let's look at potentially corresponding sides. That side to that side, to go from four to 12, we would multiply by three, and then we could look at this side and this side, to go from four to 12, once again you multiply by three, so that's looking good so far. We could look at this side and this side, potentially corresponding sides. Once again, we're going from four to 12, multiplying by three. Looks good so far. And then we could look at this side and this side. 2.2 to 6.6, once again multiplying by three. Looking really good. And then we only have one last one to check. 2.2 to 6.6, once again multiplying by three, so all of the side lengths have been scaled up by three, so we can feel pretty good that Figure B is indeed a scaled-up representation of Figure A.