document.write( "Question 28582: A rectancle JKLM is inscribed in an another rectangle ABCD such that the vertices J,K,L and M touches the side AB,BC, CD and DA respectively.where AB = 12cm and BC = 7cm. Also AJ = BK= CL= DM= x.The area of rectangle JKLM is 54cm2. Find x? \n" ); document.write( "
Algebra.Com's Answer #17369 by venugopalramana(3286)![]() ![]() You can put this solution on YOUR website! SEE DRAWING BELOW \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "LET AK=BL=CM=DN=X \n" ); document.write( "AB=CD=12 AND BC=DA=7. \n" ); document.write( "FIRSTLY KLMN WILL NOT BE A RECTANGLE.IT WILL BE PARALLELOGRAM AS YOU CAN SEE BELOW. \n" ); document.write( "LET DC BE X AXIS AND DA BE Y AXIS WITH D AS ORIGIN.HENCE COORDINATES OF DIFFERENT POINTS ARE \n" ); document.write( "D...(0,0) M..(10,0) C…(12,0) L…(12,5) B….(12,7) K….(2,7) A….(0,7) N….(0,2) \n" ); document.write( "SLOPE OF MN =(0-2)/(10-0)= -1/5 \n" ); document.write( "SLOPE OF NK =(7-2)/(2-0)= 5/2 \n" ); document.write( "PRODUCT OF SLOPES =(-1/5)*((5/2)=-1/2…..SO THEY ARE NOT PERPENDICULAR. \n" ); document.write( "SO KLMN IS NOT A RECTANGLE. \n" ); document.write( "THEN FORMULA FOR AREA ALSO CHANGES.\r \n" ); document.write( "\n" ); document.write( "LET US FIND AREAS OF 4 TRIANGLES AKN,KBL,LCM AND MDN ALL OF WHICH ARE RIGHT ANGLED TRIANGLES. \n" ); document.write( "SUM OF THEM IS 84-54=30..AS THIS IS EQUAL TO AREA OF ABCD(84) - AREA OF KLMN (54) \n" ); document.write( "SUM OF AREAS OF 4 TRIANGLES AKN,KBL,LCM AND MDN ARE \n" ); document.write( "(1/2){X(12-X)+X(7-X)+X(12-X)+X(7-X)}=X(12-X)+X(7-X)=X(12-X+7-X)=X(19-2X)=19X-2X^2=84-54=30 \n" ); document.write( "2X^2-19X+30=0 \n" ); document.write( "2X^2-4X-15X+30=0 \n" ); document.write( "2X(X-2)-15(X-2)=0 \n" ); document.write( "(X-2)(2X-15)=0 \n" ); document.write( "X-2=0….OR……X=2 \n" ); document.write( "2X-15=0….OR….X=7.5…WHICH IS BEYOND SIDES BC AND DA..SO NOT TO BE CONSIDERED. \n" ); document.write( "SO X=2 \n" ); document.write( " |