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Point $B$ is the image of point $A$ under a dilation with center $O$. If $OB = 30$, and the scale factor of the dilation is $5$, then what is $OA$?

 May 20, 2024
 #1
avatar+1837 
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This question isn't hard at all, and only involves one key fact. 

 

First, we HAVE to know the formula 

Dilation Factor = Length of Image / Length of Pre-image

 

So, now, we just plug in some numbers and we are done!

Length of AB (image) = 30 units

\(5 = 30 / OA \)

\(OA = 30/5\)

\(OA = 6\)

 

So OA is basically just 6 units. 

 

Thanks! :)

 May 20, 2024

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