A piece of wire 10 m long is cut into two pieces. One piece is bent into a squar

Boduszewox6

Boduszewox6

Answered question

2021-11-16

A piece of wire 10 m long is cut into two pieces. One piece is bent into a square and the other is bent into an equilateral triangle. How should the wire be cut so that the total area enclosed is (a) a maximum? (b) A minimum?

Answer & Explanation

James Obrien

James Obrien

Beginner2021-11-17Added 16 answers

Let the amount cut for the square be x
Then the amount left for the equilateral triangle will be 10x
Side length of the square is x4
Area of the square =(x4)2=x216
Area of an equiilateral triangle with side length a is 34a2
Side length of the equilateral triangle is 10x3
Area of the equilateral triangle is 10x3
Area of the equilateral triangle =34(10x3)2=3(10x)236
Total area = Area of square + Area of equilateral triangle
A(x)=x216+3(10x2)36
Differentiate A(x)=0
x83(10x)18=0
x8=3(10x)18
Cross Multiply
18x=83(10x)
18x=80383x
(18+83)x=803
x=80318+834.35
For maximum are all the wire, should be used to make the square.
madeleinejames20

madeleinejames20

Skilled2023-06-19Added 165 answers

Answer:
x5.767 and 10x4.233 and x8.198 and 10x1.802
Explanation:
To find the optimal wire cut, we can use mathematical reasoning. Let's denote the length of the wire used for the square as x and the length used for the equilateral triangle as 10x.
(a) To maximize the total enclosed area, we need to maximize both the square's area and the triangle's area. The area of a square is given by Asquare=x2, and the area of an equilateral triangle is given by Atriangle=34(10x)2.
To find the maximum, we can take the derivative of the total area Atotal=Asquare+Atriangle with respect to x and set it to zero:
dAtotaldx=d(x2)dx+d(34(10x)2)dx=0
Simplifying the equation, we get:
2x32(10x)=0
Solving for x, we find:
x=1034+35.767
Therefore, to maximize the enclosed area, the wire should be cut into two pieces with lengths approximately x5.767 and 10x4.233.
(b) To minimize the total enclosed area, we can follow the same approach. However, instead of setting the derivative to zero, we need to find the minimum value for the total area.
By taking the derivative of Atotal with respect to x and solving for x, we find:
x=103438.198
Hence, to minimize the enclosed area, the wire should be cut into two pieces with lengths approximately x8.198 and 10x1.802.
Mr Solver

Mr Solver

Skilled2023-06-19Added 147 answers

(a) To find the maximum total area enclosed, we need to maximize the sum of the areas of the square and the equilateral triangle.
The area of a square is given by the formula: Asquare=x2 square meters.
The area of an equilateral triangle is given by the formula: Atriangle=34a2, where a is the side length of the equilateral triangle.
Since the perimeter of the equilateral triangle is (10x) meters, we can express the side length a as: a=10x3 meters.
Substituting the value of a into the formula for the area of the equilateral triangle, we have:
Atriangle=34(10x3)2 square meters.
The total area enclosed is the sum of the areas of the square and the equilateral triangle:
Atotal=Asquare+Atriangle=x2+34(10x3)2 square meters.
To find the maximum total area, we need to take the derivative of Atotal with respect to x, set it to zero, and solve for x.
Taking the derivative of Atotal with respect to x, we get:
dAtotaldx=2x2336(10x)(1)=2x+318(10x).
Setting dAtotaldx to zero, we have:
2x+318(10x)=0.
Simplifying the equation, we get:
2x+318·10318x=0.
Combining like terms, we have:
(2318)x=318·10.
Solving for x, we get:
x=318·102318.
Simplifying the expression, we find:
x=103363.
Therefore, to maximize the total area enclosed, the wire should be cut into two pieces such that x=103363 meters is used for the square and (10x) meters is used for the equilateral triangle.
(b) To find the minimum total area enclosed, we can use the same expression for Atotal and follow a similar process to find the minimum. We can differentiate Atotal with respect to x, set it to zero, and solve for x. The obtained value of x will give the minimum total area enclosed.

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