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September 23rd, 2012, 08:23 AM  #1 
Member Joined: Sep 2012 From: Norway Posts: 35 Thanks: 0  How can I find the ratio for these two shapes?
I know that in order to figure out the unknown sides in these two triangular I have to work out the ratio. Problem 1: When I work out the ratio, how do I know which order to divide the numbers by? Ex. AB= 6 AND DE= 8. How am I supposed to know whether or not Im supposed to divide 6 by 8 or the opposite. Problem 2: I order to figure out AC my book multiplied 10 with the ratio. I thought you would have to divide as AC is the smaller triangular? 
September 23rd, 2012, 08:55 AM  #2 
Newbie Joined: Jan 2012 From: Singapore Posts: 15 Thanks: 0  Re: How can I find the ration for these two shapes?
Either order will be fine because you are finding the ratio between two lengths that are in two similar figures. You will have to stick to the order that you have initially used for the rest of the calculations. For example, you used the big triangle over the small triangle, the ratio you have found would be a A:B On the other hand, if you have small over the big one, the ratio would be B:A. Second question is just playing around with the ratio as fractions, you can try doing it again, 
September 23rd, 2012, 12:39 PM  #3 
Global Moderator Joined: May 2007 Posts: 6,807 Thanks: 716  Re: How can I find the ration for these two shapes?
You should use common sense. The triangle on the right is bigger, so the corresponding sides must be bigger. The ratio is 4/3, so going from left to right, multiply by 4/3, while going from right to left multiply by 3/4. 

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