Question 461709


The length {{{L}}} of a rectangle is five times its width {{{W}}}.

{{{L=5W}}}.........1

If the area of the rectangle {{{A=L*W=450 cm^2}}}  .....2 

find its perimeter {{{P}}}
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{{{P=2(L+W)}}}......now find {{{L}}} and {{{W}}} using equations 1 and 2

{{{L=5W}}}.........1.substitute in 2

{{{L*W=450 cm^2}}}  .....2 
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{{{5W*W=450 cm^2}}}


{{{5W^2=450 cm^2}}}

{{{W^2=450 cm^2/5}}}

{{{W^2=90 cm^2}}}

{{{W=sqrt(90 cm^2)}}}

{{{W=9.49cm}}}.......now find {{{L}}}

{{{L=5W}}}

{{{L=5*9.49cm}}}

{{{L=47.45cm}}}

check the result:

{{{A=L*W=450 cm^2}}}

{{{47.45cm*9.49cm=450 cm^2}}}

{{{450.3005cm^2=450 cm^2}}}...round it

{{{450cm^2=450 cm^2}}}

plug these values in {{{P}}}:

{{{P=2(L+W)}}}

{{{P=2(47.45cm+9.49cm)}}}

{{{P=2(56.94cm)}}}

{{{P=113.88cm}}}