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Thread: Define Variables & set up equations: Perimeter equtation

  1. #1
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    Define Variables & set up equations: Perimeter equtation

    A rectangle is 3 times as long as it is wide. Its perimeter is 80 centimeters. Find its deminsions.

    I dont know how to set it up with variables. Someone please help.
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  2. #2
    MHF Contributor arbolis's Avatar
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    Ok. You can define a side as "$\displaystyle x$". The opposite side will have a length of $\displaystyle x$ too. You are told that the 2 other sides are 3 times longer. It means their values are $\displaystyle 3x$.
    Also, we know that the perimeter is 80 cm. You can put the equation of the perimeter adding the four sides together, we get $\displaystyle 3x+3x+x+x=80$. I let you solve for x, that is the answer.
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