algebra .. seventh grade ?
How do i find the length and width of a rectangle that has the perimeter of 18 cm and a area of 18 sq meters ?
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How do i find the length and width of a rectangle that has the perimeter of 18 cm and a area of 18 sq meters ?
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Answers & Comments
First comment: get your units straight!! Considering there are 10,000 cm² in one single m², I think you'll understand that it'd be difficult to have a rectangle with exactly those properties...
Indeed, the shortest perimeter for an 18m² rectangle is in the case of the square, and it would be 4*sqrt(18) = 4*sqrt(9*2) = 4*sqrt(9)*sqrt(2) = 4*3*sqrt(2) = 12sqrt(2) ~= 16.97 M = 1697 CM
Conversely, the largest area one can get inside a rectangle with an 18cm perimeter would be (18/4)² = 4.5² = 20.25 CM² = .002025 M²
Usually when you need to find 2 values, you also have a system of 2 equations: in this case, one for the area and one for the perimeter.
with l and w being respectively the length and width of the triangle:
{2l + 2w = 18
{lw = 18
Solve one equation for one variable, then plug the result (complete with the as-yet-unknown other variable) into the other one and solve for the other variable. This should give you the actual numeric value.
Then, plug the numeric value you've just found back into one of the original equations and solve for the unknown
You can't have a perimeter of 18cm and an area of 18 sq meters.
Assume these are meters and sq meters, then
L * W = 18
2L + 2W = 18
L = 18/W
2(18/W) + 2W = 18
(18/W) + W = 9
18 + W^2 = 9W
w^2 - 9w + 18 = 0
(w-6)(w-3) = 0
width = 3; 6 (and length = 6; 3)
so dimension is 6x3
A=lw
perimeter=18=l+l+w+w
logically 6+3=9
there are two congruent sides of both l and w so there would be two sides 6 and two sides 3 for the perimeter to = 18 and the area (lw) to = 18 so your answer would be 6 and 3
oh good, i am in 7th grade algerba also. i will help you
the answer is....wait your question is unreasonable ask what you realy mean PLZ!!!
if you mean perimeter of 18 cm adn area 18 cm then.....idk srry!