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# Find the length of a rectangle if the width is 8cm and the perimeter 40cm.?

Find the length of a rectangle if the width is 8cm and the perimeter 40cm.

5cm

12cm

24cm

32cm

### 19 Answers

- Barkley HoundLv 71 decade agoFavorite Answer
The perimeter is equal to 2*width + 2*length therefore

2*8 + 2*length = 40

16 + 2*length = 40

2*length = 24

length = 12

*

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- 1 decade ago
A rectangle has two pairs of sides that are equal in length.

Perimeter = 2 * W + 2 * L

You're given the Width and the Perimeter -- so fill those in the equation:

40 = 2 * 8 + 2 * L

Now, solve for L:

40 = 2 * 8 + 2 * L -------- multiply 2 & 8, results in

40 = 16 + 2 * L ---------- subtract 16 from both sides, results in

24 = 2 * L ------------------ divide both sides by two, results in

12 = L

Try it out -- if I had an 8cm by 12cm rectangle, what would the perimeter be? 8 + 8 + 12 + 12 = ??

Cheers!

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- pheonixLv 44 years ago
W=width L=length 2W (considering rectangle has 4 aspects, 2 for width, 2 for length) + 2L = 40 (Perimeter) Plug 8 in for W because of the fact the width is 8 2(8)+2L=40 Simplify sixteen+2L=40 Subtract sixteen from the two aspects to isolate the variable 2L=40-sixteen Simplify 2L=24 Divide the two aspects by using 2 so which you will locate out purely what L equals L=24/2 L=12 *So the dimensions of the rectangle is 12* wish this helps! :)

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- 1 decade ago
(40 - 2*8) / 2 = 12 cm =]

So basically a rectangles perimeter is the sum of two times the length and two times the width. S = 2l +2w so to solve for the length l, you subtract twice the width from the perimeter and divide the entire equation by two.

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- ScottyLv 61 decade ago
12 cm. You multiply the width by 2 because there are 2 equal sides, then you subtract that from the total perimeter, then divide the balance by 2 because there are 2 equal sides left.

8 x 2 = 16

40 - 16 = 24

24 / 2 = 12

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- PeterTLv 51 decade ago
Perimeter = 2 * length + 2 * width

40 = 2 * length + 2 * 8

40 = 2 * length + 16

24 = 2 * length

length = 12 cm

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- Anonymous1 decade ago
12

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- 1 decade ago
Perimeter= 2xlength+ 2 width

40= 2L+2(8)

2L=40-16

L=24/2= 12cm

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- 1 decade ago
I am confused. Not by the question but by all of the answers. How in the world can you get 5? you dont divide or subtract so how can you get something lower than 8? and I think it is 24. I dont really know considering I'm not the brightest in math.

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