document.write( "Question 77435: (1) The perimeter of a rectangle is 100 and its diagonal has length \"x\". The area of this rectangle,is
\n" );
document.write( "(A) 625-x^2 (b) 625-(x^2)/2 (c) 1250-x^2 (d) 1250-(x^2)/2 \n" );
document.write( "
Algebra.Com's Answer #55542 by ptaylor(2198)![]() ![]() You can put this solution on YOUR website! Perimeter(P)=two times length (L) plus two times width (W) or\r \n" ); document.write( "\n" ); document.write( "P=2L+2W \n" ); document.write( "2L+2W=100 divide both sides by 2 \n" ); document.write( "L+W=50-----------------------------------eq1\r \n" ); document.write( "\n" ); document.write( "Area of rectangle (A)=length(L)*width(W) or\r \n" ); document.write( "\n" ); document.write( "A=L*W-------------------------------------eq2\r \n" ); document.write( "\n" ); document.write( "When we draw the diagonal in a rectangle we, in effect, divide the rectangle into two identical right triangles. Here, we can apply the Pythagorean Theorem:\r \n" ); document.write( "\n" ); document.write( "L^2+W^2=x^2--------------------------------eq3\r \n" ); document.write( "\n" ); document.write( "Clearly, we have enough information to solve these non-linear simultaneous equations----BUT THAT'S NOT RECOMMENDED! Instead, lets square both sides of eq1 and we get:\r \n" ); document.write( "\n" ); document.write( "(L+W)^2=50^2 \n" ); document.write( "L^2+2L*W+W^2=2500 lets rewrite this:\r \n" ); document.write( "\n" ); document.write( "L^2+W^2+2L*W=2500 but \n" ); document.write( "L^2+W^2=x^2 and \n" ); document.write( "L*W=A\r \n" ); document.write( "\n" ); document.write( "substitute these into the equation and we get:\r \n" ); document.write( "\n" ); document.write( "x^2+2A=2500 subtract x^2 from both sides\r \n" ); document.write( "\n" ); document.write( "x^2-x^2+2A=2500-x^2 collect like terms\r \n" ); document.write( "\n" ); document.write( "2A=2500-x^2 divide both sides by 2\r \n" ); document.write( "\n" ); document.write( "A=(2500-x^2)/2 \n" ); document.write( "A=1250-(x^2)/2--------------------------------ans\r \n" ); document.write( "\n" ); document.write( "Frequently, when a problem appears much too difficult, there will be an easy way to solve it\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor \n" ); document.write( " \n" ); document.write( " |