Creating scale drawings | Geometry | 7th grade | Khan Academy

Sue is a software engineer. She wants to create a large-scale drawing of a processor inside a cell phone. The processor is a square chip, nine millimeters on each side. Draw the processor such that one unit on the grid below represents one half of a millimeter.

All right, so let's just think about these two worlds: you have the drawing and you have the chip in the real world. The drawing we're thinking in terms of these units here on this graph paper, so units. And the chip, we're thinking in terms of millimeters.

So we can set up a table here, and they tell us to draw it such that one unit represents half a millimeter. So one unit would represent one half of a millimeter. They tell us that the processor is nine millimeters on each side. So that is how many times as many millimeters?

Well, to go from one half to nine, you have to multiply by 18. So that's going to be 18 times as many units as well. So if I want to do a scale drawing right over here, it's going to be a square. It's a square chip, and since the scale is one unit, it represents half a millimeter; 18 units would represent nine millimeters.

And so I would want to do 18 units on a side. So, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18. So that would be the left side of the chip. Let me just see if I can draw a straight line there, just like that.

Then it would also be 18 wide, 18 units wide, representing 9 millimeters in the real world. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18. This is making my eyes hurt.

All right, so just like that. And then I could draw the other parts of it; it would be like that. And then I would just go straight down like that. And there you have it! I have drawn a scale drawing of our processor, and we are all done.