document.write( "Question 1134281: A rectangle has a perimeter of 34cm. One of its diagonals is 13cm. Find its sides. \n" ); document.write( "
Algebra.Com's Answer #751629 by Theo(13342)![]() ![]() You can put this solution on YOUR website! the perimeter of the rectangle is 34 cm.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the formula for perimeter is 2x + 2y = p\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when p = 34, the formula becomes 2x + 2y = 34\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x is the length \n" ); document.write( "y is the width\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "one of the diagonals is 13 cm.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since it's a rectangle, the other diagonal has to be 13 as well.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's a nice fact to know but it's not necessary to know it to solve this problem.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the diagonal forms a right triangle with one of the sides being x and the other side being y.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "by pythagorus, the diagonal squared is equal to x^2 + y^2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the formula is therefore x^2 + y^2 = 13^2 which becomes x^2 + y^2 = 169.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you have two equations that needs to be solved simultaneously.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "they are 2x + 2y = 34 and x^2 + y^2 = 169.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for y in the first equation to get y = 17 - x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "replace y with 17 - x in the second equation to get x^2 + (17 - x)^2 = 169\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "simplify to get x^2 + x^2 - 34x + 289 = 169\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 169 from both sides of that equation to get x^2 + x^2 - 34x + 120 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "combine like terms to get 2x^2 - 34x + 120 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "divide both sides of the equation by 2 to get x^2 - 17x + 60 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "factor that equation to get (x - 5) * (x - 12) = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that makes x = 5 or x = 12.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since y = 17 - x, .....\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when x = 5, y = 12 \n" ); document.write( "when x = 12, y = 5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since x is the length of the rectangle, let x = 12. \n" ); document.write( "you have length of the rectangle is 12 and width of the rectangle is 5.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the perimeter is equal to 2 * 12 + 2 * 5 = 24 + 10 = 35 cm which is correct.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x^2 + y^2 = 13^2 becomes 12^2 + 5^2 = 169 which becomes 144 + 25 = 169 which becomes 169 = 169 which is true.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the solution looks good.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the solution is that the length of the rectangle is 12 and the width of the rectangle is 5.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's a good reference on the properties of a rectangle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "https://brilliant.org/wiki/properties-of-rectangles/\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |