document.write( "Question 1043677: Find the dimensions and area of the largest rectangle that can be inscribed in a right angle triangle, whose sides have lengths of 9cm, 12cm and a hypotenuse of 15cm. \n" ); document.write( "
Algebra.Com's Answer #659021 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
Find the dimensions and area of the largest rectangle that can be inscribed in a right angle triangle, whose sides have lengths of 9cm, 12cm and a hypotenuse of 15cm.
\n" ); document.write( ":
\n" ); document.write( "let x = the width of the rectangle
\n" ); document.write( "let y = the length
\n" ); document.write( ":
\n" ); document.write( "Draw out a right triangle with the rectangle inscribed therein, x by y
\n" ); document.write( "the height of the right triangle = 12 and the base = 9
\n" ); document.write( ":
\n" ); document.write( "We are interested in the small right triangles adjacent the inscribed rectangle
\n" ); document.write( "The tangent of the top angle = 9/12 which = \"x%2F%28%2812-y%29%29\" of the small right triangle on top
\n" ); document.write( "Cross multiply
\n" ); document.write( "12x = 9(12-y)
\n" ); document.write( "12x = 108 - 9y
\n" ); document.write( "x = 9 - \"9%2F12\"y
\n" ); document.write( "similarly, the tangent of the base angle = 12/9 = \"y%2F%28%289-x%29%29\"
\n" ); document.write( "Cross multiply
\n" ); document.write( "9y = 12(9-x)
\n" ); document.write( "9y = 108 - 12x
\n" ); document.write( "y = 12 - \"12%2F9\"x
\n" ); document.write( ":
\n" ); document.write( "Area = xy
\n" ); document.write( "replace y with (12-\"12%2F9\"x)
\n" ); document.write( "A = x(12-\"12%2F9\"x)
\n" ); document.write( "A = 12x - \"12%2F9\"x^2
\n" ); document.write( "A quadratic equation, max occurs at the axis of symmetry; x=-b/(2a)
\n" ); document.write( "x = \"%28-12%29%2F%282%28-12%2F9%29%29\"
\n" ); document.write( "x = \"%28-12%29%2F%28-24%2F9%29\"
\n" ); document.write( "x = +4.5 cm is the width of the rectangle with max area
\n" ); document.write( ":
\n" ); document.write( "Find y
\n" ); document.write( "y = 12 - \"12%2F9\"*4.5
\n" ); document.write( "y = 12 - 6
\n" ); document.write( "y = 6 cm is length
\n" ); document.write( ":
\n" ); document.write( "Max area: 6 * 4.5 = 27 sq/cm
\n" ); document.write( ":
\n" ); document.write( "NOt sure if I explained this clearly, let me know. CK
\n" ); document.write( "
\n" );