# A square has a perimeter of 20 cm what is the length of its diagonal rounded to the nearest tenth

multiply the length of one side by the square root of 2. 20√2 = 28.28 Rounded to the nearest tenth: 28.28→28.3 28.3 is the final answer

-- All 4 sides of a square are the same length. The perimeter is 20 cm. So each side is (20/4) = 5 cm. -- If you cut the square along its diagonal, and throw one piece away ... You have a right triangle. The legs are sides of the square ... 5 cm each. The hypotenuse is the diagonal of the square, which you have to find. -- The (hypotenuse of any right triangle)² = (the length of one leg)² + (the length of the other leg)² . (Diagonal)² = (5 cm)² + (5 cm)² (Diagonal)² = (25 cm²) + (25 cm²) (Diagonal)² = (50 cm²) Diagonal = √(50 cm²) = 7.07 cm or 7.1 cm rounded to the nearest tenth.