SOLUTION: The perimeter of a rectangular floor is 42 feet, and the area is 108 square feet. Find the length of the floor.

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: The perimeter of a rectangular floor is 42 feet, and the area is 108 square feet. Find the length of the floor.      Log On


   



Question 4269: The perimeter of a rectangular floor is 42 feet, and the area is 108 square feet. Find the length of the floor.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Assign the variables: Let x = the length of the side of the square.
Then x+6 = the length of the diagonal.
Apply the Pythagorean theorem: c^2 = a^2 + b^2 c is the diagonal, a and b are the sides of the square.
(x+6)^2 = x^2 + x^2
x^2 + 12x + 36 = 2x^2 Subtract x^2 from both sides.
12x + 36 = x^2 Rewrite in standard quadratic form.
x^2 - 12x - 36 = 0 Solve the quadratic using the quadratic formula.
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F2a%29
x=%2812%2B-sqrt%28-12%5E2-4%2A36%29%29%2F2%29