A rectangular skating rink measures 40m by 20m It is to be doubled in area by extending each side by the same amount determine how much each side should be extended?

Answer 1

Present area is 40 x 20 ie 800 sq m. Required area is therefore 1600 sq m. ie (40 + n) x (20 + n) = 1600 where n is the increase in side so 800 +60n + n squared = 1600 which is the same as n squared + 60n - 800 = 0 using the quadratic formula gives -60 plus or minus the square root of (60 squared - 4 x 1 x -800) all dividied by 2 which is (-60 plus or minus 82.46)/2 = -30 + 41.23 = 11.23 so the sides must be extended to 51.23 x 31.23 giving an area of 1599.9, near enough for the Government.