Scale Factors

Scale Factor

Now you try, did this potion make a person grow or shrink? Answer on the next slide.

Poll

So did the potion make the person grow or shrink?

• Grow

• Shrink

Now you try, did this potion make a person grow or shrink? Answer on the next slide.

Poll

So did the potion make the person grow or shrink?

• Grow

• Shrink

Using Scale Factors:

• When given a scale factor we multiply that number to the original dimensions to find the new dimensions.

• For Example, 15 x  $\frac{2}{5}$  = 6

•  $35\ \cdot\ \frac{2}{5}\ =14$  

• Therefore our new box will have dimensions of 6 in. by 14 in.

Multiple Choice

You try to find the new dimensions of the box. Click the picture to zoom.

• 2.8 in. by 6.3 in

• 30 in. by 66 in.

• 35 in. by 77 in.

• 3.5 in. by 7.7 in.

Multiple Choice

You try to find the new dimensions of the box. Click the picture to zoom.

• 40 by 50 in

• 4 by 5 in

• 14.4 in by 18 in

• 1.4 in by 1.8 in

Finding Scale factors

To find scale factors, we divide the new image by the old image.
(We use ' to represent the new image we call H', H prime)

So, our scale factor here would be:

 $\frac{H'G'}{HG}=\frac{10}{8}=\frac{5}{4}$  

Multiple Choice

You try now. What is the scale factor of the rectangles in the image

• 3/2

• 2/3

• 1

• 3/4

The End

(or is it...?)

No, no it's not.