Final answer:
The length of a side in a square with a diagonal of 20 is 10√2.
Step-by-step explanation:
Given a square with a diagonal of 20, we can use the Pythagorean theorem to find the length of a side. The Pythagorean theorem states that in a right triangle, the square of the length of the hypotenuse (diagonal in this case) is equal to the sum of the squares of the other two sides. Since a square has four equal sides, we can let the length of a side be 'x'.
Using the Pythagorean theorem, we have:
x^2 + x^2 = 20^2
2x^2 = 400
x^2 = 200
x = √200 = √(100 * 2) = 10√2
Therefore, the length of a side of the square is 10√2.