document.write( "Question 934802: A right triangle has a fixed hypotenuse of 30 cm. And the other two sides are allowed to vary. Determine the largest possible area of the triangle.
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Algebra.Com's Answer #567838 by KMST(5328)\"\" \"About 
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\"x\"= length of one leg, in cm.
\n" ); document.write( "\"y\"= length of the other leg, in cm.
\n" ); document.write( "}}}According to the Pythagorean theorem,
\n" ); document.write( "\"x%5E2%2By%5E2=30%5E2\"<--->\"x%5E2%2By%5E2=900\"<--->\"y%5E2=900-x%5E2\"
\n" ); document.write( "The area of the right triangle, in \"cm%5E2\" is
\n" ); document.write( "\"area=%281%2F2%29%2Ax%2Ay\",
\n" ); document.write( "so \"area%5E2=%28%281%2F2%29%2Ax%2Ay%29%5E2\"
\n" ); document.write( "\"area%5E2=%281%2F2%29%5E2%2Ax%5E2%2Ay%2A2\"
\n" ); document.write( "\"area%5E2=%281%2F4%29%2Ax%5E2%2Ay%2A2\"
\n" ); document.write( "Substituting the expression \"900-x%5E2\" (found above) for \"y%5E2\" we get
\n" ); document.write( "\"area%5E2=%281%2F4%29%2Ax%5E2%2A%28900-x%5E2%29\"<---->\"area%5E2=%281%2F4%29%28-x%5E4%2B900x%5E2%29\"<---->\"area%5E2=%281%2F4%29%28-%28x%5E2%29%5E2%2B900x%5E2%29\"
\n" ); document.write( "That last expression shows \"area%5E2\" a as quadratic function of \"x%5E2%29\" ,
\n" ); document.write( "and we know that it will have a maximum when \"x%5E2=900%2F2\"<--->\"x%5E2=450\" .
\n" ); document.write( "For that value of \"x%5E2\" ,
\n" ); document.write( "\"area%5E2=%281%2F4%29%28-450%5E2%2B900%2A450%29\"
\n" ); document.write( "\"area%5E2=%281%2F4%29%2A450%2A%28-450%2B900%29\"
\n" ); document.write( "\"area%5E2=%281%2F4%29%2A450%2A450\"
\n" ); document.write( "\"area%5E2=%281%2F4%29%2A450%5E2\"
\n" ); document.write( "\"area%5E2=450%5E2%2F2%5E2\"
\n" ); document.write( "\"area%5E2=%28450%2F2%29%5E2\"
\n" ); document.write( "\"area%5E2=225%5E2\"
\n" ); document.write( "\"highlight%28area=225%29\" and that is the largest possible area of the triangle, in square centimeters.
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