document.write( "Question 194553: A wire 20 feet long is to be cut into two pieces. one pierce will be shaped as a square and the other piece will be shaped as an equilateral triangle. express the total area A enclosed by by the piece of wire as a function of the length x of a side of the equilateral triangle. what is the domain of A? for what value of x will the total area A be the smallest?
\n" ); document.write( "please i need help. please help me please.....
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Algebra.Com's Answer #146040 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
If \"x\" is a side of the equilateral triangle,
\n" ); document.write( "then the length of wire used for the triangle is
\n" ); document.write( "\"3x\" ft
\n" ); document.write( "The length of wire left over for the square is
\n" ); document.write( "\"20+-+3x\" ft
\n" ); document.write( "One side of that square would be
\n" ); document.write( "\"%2820+-+3x%29%2F4\" ft
\n" ); document.write( "If \"A\" is the total area, then
\n" ); document.write( "\"A+=+sqrt%283%29%2A%28x%2F2%29%5E2+%2B+%28%2820+-+3x%29%2F4%29%5E2\"
\n" ); document.write( "\"A+=+sqrt%283%29%2A%28x%2F2%29%5E2+%2B+%28%2820+-+3x%29%2F4%29%5E2\"
\n" ); document.write( "\"A+=+%28%28sqrt%283%29%29%2F4%29%2Ax%5E2+%2B+%28400+-+120x+%2B+9x%5E2%29+%2F+16\"
\n" ); document.write( "Multiply both sides by \"16\"
\n" ); document.write( "\"16A+=+4%2Asqrt%283%29%2Ax%5E2+%2B+%28400+-+120x+%2B+9x%5E2%29%2F16\"
\n" ); document.write( "\"A+=+%28sqrt%283%29%2F4+%2B+9%29%2Ax%5E2+-+120x+%2B+400\"
\n" ); document.write( "-------------------------------------------
\n" ); document.write( "If \"x+=+0\", or I had no triangle at all, then
\n" ); document.write( "\"A+=+400\", as it should, since the whole \"20\" ft
\n" ); document.write( "is being used by the squareand \"A+=+20%5E2\"
\n" ); document.write( "If \"x+=+20%2F3\", then nothing is left for the square, and
\n" ); document.write( "all the area is used by the triangle.
\n" ); document.write( "I'll check this:
\n" ); document.write( "\"A+=+sqrt%283%29%2A%28x%2F2%29%5E2+\"
\n" ); document.write( "\"A+=+1.732%2A%2820%2F6%29%5E2\"
\n" ); document.write( "\"A+=+1.732%2A11.111\"
\n" ); document.write( "\"A+=+19.244\" ft2
\n" ); document.write( "and
\n" ); document.write( "\"A+=+%28sqrt%283%29%2F4+%2B+9%29%2Ax%5E2+-+120x+%2B+400\"
\n" ); document.write( "\"A+=+%28sqrt%283%29%2F4+%2B+9%29%2A%2820%2F3%29%5E2+-+120%2A%2820%2F3%29+%2B+400\"
\n" ); document.write( "\"A+=+%28sqrt%283%29%2F4+%2B+9%29%2A%28400%2F9%29+-+800+%2B+400\"
\n" ); document.write( "\"A+=+100%2Asqrt%283%29%2F9+%2B+400+-+800+%2B+400+\"
\n" ); document.write( "\"A+=+19.244\" ft2
\n" ); document.write( "The domain of \"A\" is 19.244 < A < 400
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\n" ); document.write( "When an equation is of the form
\n" ); document.write( "\"ax%5E2+%2B+bx+%2B+c\", the minimum is at \"x+=+-%28b%2F%282a%29%29\"
\n" ); document.write( "In this case,
\n" ); document.write( "\"b+=+-120\"
\n" ); document.write( "\"a+=+sqrt%283%29%2F4+%2B+9\"
\n" ); document.write( "\"-%28b%2F%282a%29%29+=+-%28-120%29%2F%282%2A%28sqrt%283%29%29%2F4+%2B+18%29\"
\n" ); document.write( "\"-%28b%2F%282a%29%29+=+120+%2F+18.866\"
\n" ); document.write( "\"-%28b%2F%282a%29%29+=+6.361\" ft
\n" ); document.write( "This is the value of \"x\" for which \"A\" is a minimum
\n" ); document.write( "I'll graph the function to check this (approximately)
\n" ); document.write( "\"+graph%28+500%2C+500%2C+-5%2C+16%2C+-15%2C+450%2C+9.433x%5E2+-+120x+%2B+400%29+\"
\n" ); document.write( "And here's a close-up
\n" ); document.write( "\"+graph%28+600%2C+600%2C+-2%2C+9%2C+-5%2C+25%2C+9.433x%5E2+-+120x+%2B+400%29+\"
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