document.write( "Question 935727: A single piece of rectangular cardboard can be folded around a 5” by 7” photo and taped along the seams to create a protective cover suitable for mailing. If the cardboard is folded as shown with no gap or overlap, find the dimensions of the original cardboard. Round to the nearest hundredth. (HINT: Use Theorem 6.9 states: In a right triangle, the altitude to the hypotenuse is the mean proportional between the two segments formed by the altitude on the hypotenuse.)\r
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Algebra.Com's Answer #569016 by TimothyLamb(4379)\"\" \"About 
You can put this solution on YOUR website!
A = small right triangle with 5\" hypotenuse
\n" ); document.write( "B = large right triangle with 7\" hypotenuse
\n" ); document.write( "---
\n" ); document.write( "x = short side of A:
\n" ); document.write( "y = long side of A:
\n" ); document.write( "z = short side of B:
\n" ); document.write( "w = long side of B:
\n" ); document.write( "---
\n" ); document.write( "triangles A and B together form a third triangle similar to A and similar to B, but larger than A, lets call this third triangle C
\n" ); document.write( "---
\n" ); document.write( "u = hypotenuse of C:
\n" ); document.write( "u = sqrt( 5*5 + 7*7 )
\n" ); document.write( "u = 8.60232526704
\n" ); document.write( "---
\n" ); document.write( "use the proportionality of similar triangles A and C:
\n" ); document.write( "(short side of A)/(hypotenuse of A) = (short side of C)/(hypotenuse of C)
\n" ); document.write( "x/5 = 5/u
\n" ); document.write( "x/5 = 5/u
\n" ); document.write( "x = 5*5/u
\n" ); document.write( "x = 5*5/8.60232526704
\n" ); document.write( "x = 2.9061909686
\n" ); document.write( "---
\n" ); document.write( "use the proportionality of similar triangles A and C:
\n" ); document.write( "(long side of A)/(hypotenuse of A) = (long side of C)/(hypotenuse of C)
\n" ); document.write( "y/5 = 7/u
\n" ); document.write( "y = 5*7/u
\n" ); document.write( "y = 5*7/8.60232526704
\n" ); document.write( "y = 4.06866735603
\n" ); document.write( "---
\n" ); document.write( "use the proportionality of similar triangles B and C:
\n" ); document.write( "(short side of B)/(hypotenuse of B) = (short side of C)/(hypotenuse of C)
\n" ); document.write( "z/7 = 5/u
\n" ); document.write( "z = 7*5/u
\n" ); document.write( "z = 7*5/8.60232526704
\n" ); document.write( "z = 4.06866735603
\n" ); document.write( "---
\n" ); document.write( "use the proportionality of similar triangles B and C:
\n" ); document.write( "(long side of B)/(hypotenuse of B) = (long side of C)/(hypotenuse of C)
\n" ); document.write( "w/7 = 7/u
\n" ); document.write( "w = 7*7/u
\n" ); document.write( "w = 7*7/8.60232526704
\n" ); document.write( "w = 5.69613429845
\n" ); document.write( "---
\n" ); document.write( "the folding corners of the cardboard are just similar copies of triangles A and B:
\n" ); document.write( "---
\n" ); document.write( "dimensions of the cardboard:
\n" ); document.write( "---
\n" ); document.write( "length of top-left edge = length of bottom-right edge = y + z
\n" ); document.write( "y + z = 4.06866735603 + 4.06866735603
\n" ); document.write( "y + z = 8.13733471206
\n" ); document.write( "---
\n" ); document.write( "length of top-right edge = length of bottom-left edge = x + w
\n" ); document.write( "x + w = 2.9061909686 + 5.69613429845
\n" ); document.write( "x + w = 8.60232526705
\n" ); document.write( "---
\n" ); document.write( "answer:
\n" ); document.write( "L = 8.60 inches
\n" ); document.write( "W = 8.14 inches
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