Question 612760
We know that to get the area of a square, we use {{{s^2=a}}}. In this case, we know the area, not the side. We have to find the side by plugging in what we know and isolating the variable. {{{s^2=400}}}. So, to find s, we take the square root of 400 which is 20. Now we know that each side of the square is 20 cm. To find perimeter, you just multiply a side by 4 (in the case of a square). {{{20*4=80}}}. The perimeter is 80 centimeters.

<p>We know that the length is the same as the square's, plus 8. {{{s+8}}}. Let's plug in what we know from before: {{{20+8=28}}}. So, the length of the rectangle is 28. What is the width? We know that the perimeter of the rectangle is the same as the square. To find the perimeter of a rectangle, the formula is {{{2l+2w=p}}}. Let's plug in what we know: {{{2(28)+2w=80}}}
Simplify: {{{56+2w=80}}} to {{{2w=24}}} to {{{w=12}}}
Now we know that the width is 12 and the length is 28. To find the area, you use this formula: {{{l*w=a}}}. Let's plug in what we know {{{12*28=336}}}

<p>So, the area of the rectangle is <b>336 cm</b>.