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In a triangle, one side is twice as long as the shortest side and another is two inches less than four times the shortest side. If the perimeter of the triangle is 33 inches, what are the side lengths?    

 

Let's call the three sides of this triangle A, B, and C  

 

Let's let C be the shortest side.  No particular reason, I just picked one.  

 

Now "one side is twice as long as the shortest side" so let's let this side be A     thus  A  =  2C                   (1)

 

And "another is two inches less than four times the shortest side"                       thus  B  =  4C – 2             (2)

 

And finally "the perimeter of the triangle is 33 inches"                                          thus  A + B + C  =  33  

 

Can you solve it now, by the substitution method?  I'll get you started. 

 

Start with the A+B+C and substitute for A and B                                                     A  +      B      + C  =  33

 

Substitute terms from (1) and (2)                                                                           2C + (4C – 2) + C  =  33  

 

Add up all the C's                                                                                                   7C          – 2           =  33    

 

Add 2 to both sides of the equation                                                                        7C                          =  35  

 

Divide both sides by 7                                                                                                                       C  =  5    

 

Now go back up and substitute 5 for C in the equalities for A and B.                        A  =  10   and   B  =  18  

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Sep 13, 2020
Sep 12, 2020
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Sep 12, 2020

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