SOLUTION: A piece of wire having a total length of 72 cm was cut into two unequal segments and bent to form two unequal squares. If the total area of the squares is 180-sq.cm.,what is the di

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Question 110067: A piece of wire having a total length of 72 cm was cut into two unequal segments and bent to form two unequal squares. If the total area of the squares is 180-sq.cm.,what is the difference in the lengths of the two segments?
Found 2 solutions by Edwin McCravy, MathLover1:
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
A piece of wire having a total length of 72 cm was cut into two unequal segments and bent to form two unequal squares. If the total area of the squares is 180-sq.cm.,what is the difference in the lengths of the two segments?

We start with this 72 cm piece of wire

drawing%28400%2C100%2C-10%2C80%2C-15%2C15%2C+line%280%2C0%2C72%2C0%29+%29

Now we cut it into two unequal parts like this:

 

Now we bend each piece into a square:

 

Now we label each side of the first square x and each side of
the second square y:

 

Each square has 4 sides, so the perimeter of the first square is 4x,
and the perimeter of the second square is 4y, and we know the sum of
all their sides total up to the length of the original wire, or 72 cm.
So we have the equation:

4x + 4y = 72

The area of the first square is x², and the area of the second square
is y² and we are told that the sum of their areas is 180. So we also 
have this equation:

x² + y² = 180
 
So we have
the system of equations:

4x + 4y = 72
x² + y² = 180

Can you solve these? Solve the first equation
for y and substitute it in the second equation.
Then you have a quadratic equation.  You get
x = 12, x = 6

Then substitute these in the first equation
and get
y = 6, y = 12

So there seem to be two solutions,

(x,y) = (12,6) and (x,y) = (6,12)

but the first is just the case when the bigger
square is on the left and the second case is
the same except the smaller square is on the left.

So the way I have the picture drawn, the big piece
of wire is the sum of the 4 sides of the big square
or 12Χ4 or 48 cm and the sum of the 4 sides of the
little square is 6Χ4 or 24 cm.  So the difference
between the pieces of wire is 48-24 or 24 cm.

Edwin


Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

A piece of wire having a total length of 72 cm was cut into two unequal segments and bent to form two unequal squares. If the total area of the squares is 180-sq.cm.,what is the difference in the lengths of the two segments?

Area_of_Square1=+x%5E2
Area_of_Square2=+y%5E2
a+_total+_length_+of+_wire+=+72+cm………=> +P1+%2B+P2+=+72cm
the_+total_+area+_of_+the+squares+=+180cm%5E2
if +P1+%2B+P2+=72cm……..=> …4x+%2B+4y+=+4%28x+%2B+y%29+=+72cm…then
=>……x%2By+=+%2872%2F4%29cm
=>……x%2By+=+18cm
=>……x=+18cm+-+y……….. substitute in formula of total area
the_+total_+area+_of_+the+squares+=+180cm%5E2
+the_+total_+area+_of_+the+squares+=+Area_of_Square1+%2B+Area_of_Square2+
180cm%5E2=+x%5E2+%2B+y%5E2
180cm%5E2=+%2818cm+-+y+%29%5E2+%2B+y%5E2
180cm%5E2=+18%5E2cm%5E2+-+36+ycm+%2B+y+%5E2+%2B+y%5E2
180cm%5E2+-+324cm%5E2+=++-+36+ycm+%2B+y+%5E2+%2B+y%5E2
-144cm%5E2+=++-+36+ycm+%2B+y+%5E2+%2B+y%5E2………….move -144cm%5E2 to the right
0+=++2y+%5E2+-+36+ycm+%2B+144cm%5E2+………….divide both sides by 2
0+=++y+%5E2+-+18+ycm+%2B+72cm%5E2+………….
Or
+y+%5E2+-+18+ycm+%2B+72cm%5E2+=+0+………….
Use quadratic formula:
y%5B1%2C2%5D=%28-b+%2B-+sqrt+%28b%5E2+-4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29
y%5B1%2C2%5D=%28-%28-18%29+%2B-+sqrt+%28%28-18%29%5E2+-4%2A1%2A72+%29%29+%2F+%282%2A1%29
y%5B1%2C2%5D=%2818+%2B-+sqrt+%28324+-+288%29%29+%2F+2

y%5B1%2C2%5D=%2818+%2B-+sqrt+%2836%29%29+%2F+2
y%5B1%2C2%5D=%2818+%2B-+6%29+%2F+2
We need only positive root
y%5B1%5D=%2818+%2B+6%29+%2F+2
y%5B1%5D=+24+%2F+2
y%5B1%5D=+12cm
Then x is:

x=+18cm+-+y………..
x=+18cm+%96+12cm………..
x=+6cm………..

Perimeter of each square P1 and P2 is:
P1+=+4+x+cm
P1+=+4+%2A6+cm

P1+=+24+cm

And
P2+=+4ycm
P2+=+4%2A12cm
P2+=+48cm
Check:
a+_total+_length_+of+_wire+=+72+cm………
P1+%2B+P2+=+72cm
=> 24cm+%2B+48cm+=+72cm
=> 72cm+=+72cm